Zapalenie mieszków włosowych – Patofizjologia i mechanizm

Zapalenie mieszków włosowych
Patofizjologia i mechanizm

Zapalenie mieszków włosowych (folliculitis) to stan zapalny obejmujący powierzchowne lub głębokie partie mieszków włosowych, wywołany przez różnorodne czynniki infekcyjne (najczęściej Staphylococcus aureus, Pseudomonas aeruginosa serotyp O:11, Malassezia spp., wirusy herpes simplex, roztocza Demodex folliculorum) oraz nieinfekcyjne (urazy mechaniczne, okluzja, reakcje polekowe). Patogeneza jest wieloczynnikowa i obejmuje mechanizmy immunologiczne, takie jak odpowiedź komórkowa (przewaga limfocytów T pomocniczych), humoralna, a także przesunięcie w kierunku odpowiedzi Th2, co jest szczególnie istotne w eozynofilowym zapaleniu mieszków włosowych (EPF). Warto podkreślić rolę dysbiozy mikrobioty skórnej, zwłaszcza w folliculitis decalvans, gdzie przewlekły stan zapalny jest podtrzymywany przez nieprawidłową rekrutację komórek układu odpornościowego i obecność bakterii oportunistycznych. Czynniki środowiskowe, takie jak nadmierne pocenie się, okluzja skóry, urazy mechaniczne oraz ekspozycja na zanieczyszczoną wodę (np. woda o pH 7,8 i niskim poziomie chloru 0,5 mg/L sprzyjająca zakażeniom Pseudomonas aeruginosa), również odgrywają istotną rolę w rozwoju choroby.

Patogeneza zapalenia mieszków włosowych

Mechanizmy infekcyjne
Mechanizmy nieinfekcyjne
Specyficzne formy zapalenia mieszków włosowych
Mechanizmy immunologiczne w zapaleniu mieszków włosowych
Histopatologia zapalenia mieszków włosowych

Rola czynników środowiskowych
Rola leków w patogenezie zapalenia mieszków włosowych
Mechanizmy molekularne w zapaleniu mieszków włosowych
Mikrobiom skórny a zapalenie mieszków włosowych
Zespół okluzji mieszkowej
Podsumowanie mechanizmów patogenetycznych

Kolejne rozdziały

Patogeneza zapalenia mieszków włosowych

Zapalenie mieszków włosowych (folliculitis) to stan zapalny mieszków włosowych, który może obejmować ich powierzchowną lub głęboką część. Jest to powszechny problem skórny charakteryzujący się obecnością grudek i/lub krostek zlokalizowanych wokół mieszków włosowych na skórze owłosionej. Patogeneza tego schorzenia jest złożona i może wynikać z różnych czynników ¹².

Mechanizmy infekcyjne

Najczęstszą przyczyną zapalenia mieszków włosowych są czynniki infekcyjne. Proces patologiczny rozpoczyna się od wprowadzenia patogenu skórnego do mieszka włosowego. Mieszki włosowe mogą również zostać uszkodzone przez tarcie ubrań, ukąszenia owadów, zablokowanie mieszka, golenie lub bardzo ciasne warkocze przylegające do skóry głowy ³⁴.

Bakteryjne zapalenie mieszków włosowych – najczęściej spowodowane przez Staphylococcus aureus, który jest częścią normalnej flory skóry. W patogenezie bakteryjnego zapalenia mieszków włosowych bakterie gronkowca dostają się do mieszków przez ujście mieszka włosowego, tworząc powierzchowne zakażenie w naskórku otaczającym kanał mieszkowy, co prowadzi do powstania krosty. Pacjenci, którzy są nosicielami gronkowca w nosie i na skórze, są bardziej podatni na rozwój tego schorzenia ⁵⁶.
Zapalenie mieszków włosowych spowodowane przez Pseudomonas aeruginosa (tzw. hot tub folliculitis) – występuje po ekspozycji na zaniemieczoną wodę. Serotyp O:11 bakterii P. aeruginosa jest najczęściej izolowanym szczepem w przypadkach zapalenia mieszków włosowych związanych z wodą. Bakterie te dostają się do mieszków włosowych przez niewielkie uszkodzenia skóry. Gorąca woda, wysokie pH (7,8) i niski poziom chloru (0,5 mg/L) sprzyjają rozwojowi zakażenia ⁷.
Grzybicze zapalenie mieszków włosowych – najczęstszym drożdżakiem powodującym zapalenie mieszków włosowych jest Malassezia (dawniej Pityrosporum). Grzyby te są lipofilne i rozwijają się w obszarach bogatych w łój, takich jak skóra głowy i tułowia, ze względu na ich zależność od zewnętrznych długołańcuchowych kwasów tłuszczowych, których nie mogą syntetyzować samodzielnie ⁸⁹.
Wirusowe zapalenie mieszków włosowych – rzadsze, ale może wystąpić, gdy zakażenie wirusem opryszczki zwykłej rozprzestrzenia się na pobliskie mieszki włosowe, pojawiając się w grupach lub skupiskach, głównie wokół ust ¹⁰.
Nużycowe zapalenie mieszków włosowych – spowodowane przez nadmierny rozrost Demodex folliculorum, roztocza żyjącego w ludzkich mieszkach włosowych ¹¹.

Mechanizmy nieinfekcyjne

Zapalenie mieszków włosowych może również wynikać z przyczyn nieinfekcyjnych, takich jak ¹²:

Uraz mechaniczny mieszków włosowych – może powstać w wyniku golenia, woskowania, elektrolizy lub wyrywania włosów, co prowadzi do podrażnienia i stanu zapalnego ¹³.
Okluzja (zablokowanie) mieszków włosowych – może być spowodowana nadmiernym poceniem się, stosowaniem okluzyjnych kosmetyków lub noszeniem ciasnych ubrań ¹⁴.
Polekowe zapalenie mieszków włosowych – może być wywołane przez niektóre leki, takie jak kortykosteroidy (trądzik steroidowy), androgeny, hormon adrenokortykotropowy (ACTH), lit, izoniazyd, fenytoinę i witaminy z grupy B ¹⁵.

Specyficzne formy zapalenia mieszków włosowych

Eozynofilowe zapalenie mieszków włosowych

Eozynofilowe zapalenie mieszków włosowych (EPF) to specyficzny typ zapalenia mieszków włosowych, który może wystąpić u osób z obniżoną odpornością, takich jak osoby zakażone wirusem HIV lub chorujące na nowotwory. Patogeneza tego schorzenia nie jest w pełni poznana, ale sugeruje się, że może być związana z procesem autoimmunologicznym skierowanym przeciwko komórkom łojowym lub jakiemuś składnikowi łoju ¹⁶¹⁷.

Badania histologiczne wykazują, że w infiltracie zapalnym w okolicy okołomieszkowej i osłonce zewnętrznej mieszka włosowego przeważają eozynofile, czemu towarzyszą zmiany gąbczaste. Często obecny jest również infiltrat okołonaczyniowy i śródmiąższowy z domieszką limfocytów i eozynofili, przy czym specjalne barwienia na obecność mikroorganizmów są negatywne ¹⁸.

Sugeruje się, że przesunięcie w kierunku odpowiedzi immunologicznej typu Th2 może być możliwym mechanizmem patogenetycznym odpowiedzialnym za infiltrację eozynofili. W patogenezie EPF podejrzewano aktywność gruczołów łojowych jako przyczynę akumulacji eozynofili w mieszkach włosowych, ponieważ zmiany ograniczają się do obszarów bogatych w łój, a wielu pacjentów ma w wywiadzie trądzik pospolity ¹⁹.

Pseudofolliculitis barbae

Pseudofolliculitis barbae (PFB), znane również jako „zapalenie mieszków włosowych brody” lub „swędzenie fryzjera”, to stan zapalny mieszków włosowych w obszarze brody, zwykle górnej wargi. Golenie nasila ten stan ²⁰.

Patogeneza PFB jest uważana za wieloczynnikową, ale zidentyfikowano dwa główne procesy odpowiedzialne za początkowy rozwój zmian PFB: penetrację przezmieszkową i penetrację pozamieszkową:

Penetracja przezmieszkowa – występuje, gdy końcówka włosa nie wychodzi przez warstwę naskórka, ale zamiast tego zagina się w dół i nadal rośnie, ostatecznie przebijając skórę właściwą, co powoduje reakcję zapalną. Naciąganie skóry podczas golenia, używanie pęset do wyrywania włosów i golenie maszynkami wieloostrzowymi, które pozostawiają końcówkę włosa w mieszku poniżej powierzchni skóry, może prowadzić do penetracji przezmieszkowej ²¹.
Penetracja pozamieszkowa – prawdopodobnie rozwija się po użyciu maszynki jednoostrzowej, która przecina łodygę włosa na powierzchni naskórka. Świeżo ścięty włos, teraz z zaostrzoną końcówką, zwija się z powrotem do naskórka w niewielkiej odległości od mieszka i nadal rośnie w dół, penetrując warstwę naskórka. Podobnie jak w przypadku penetracji przezmieszkowej, następuje reakcja zapalna typu ciała obcego, powodująca ból, stan zapalny i klasyczną zmianę PFB ²².

Wykazano, że wspólny polimorfizm w genie keratyny (K6hf) jest powiązany z PFB, co sugeruje, że może być genetycznym czynnikiem ryzyka. Ta zmiana sekwencji prowadzi do zamiany aminokwasu w wysoce konserwatywnym motywie inicjacji helisy domeny pręta K6hf. Nosiciele polimorfizmu A12T są sześć razy bardziej narażeni na rozwój PFB w porównaniu z osobami homozygotycznymi pod względem sekwencji dzikiego typu K6hf. To sugeruje, że mutacja K6hf strukturalnie osłabia warstwę towarzyszącą oddzielającą wewnętrzną i zewnętrzną osłonkę korzenia i zwiększa szanse na wrastanie włosa brody ²³.

Folliculitis decalvans

Folliculitis decalvans to rzadkie neutrofilowe łysienie bliznowaciejące skóry głowy. Jest to postępująca choroba zapalna charakteryzująca się stopniowym zwiększaniem się obszaru zapalonych mieszków włosowych z tworzeniem obszarów łysienia bliznowaciejącego ²⁴.

Dokładna przyczyna folliculitis decalvans nie jest w pełni zrozumiała, ale uważa się, że Staphylococcus aureus może odgrywać rolę w jej rozwoju. Obecna wiedza na temat patogenezy folliculitis decalvans sugeruje trzy etapy obejmujące nadaktywację odporności wrodzonej, zakażenie bakteryjne i zwłóknienie jako wynik choroby ²⁵.

Wcześniej sugerowano, że Staphylococcus aureus odgrywa główną rolę w patogenezie choroby, ale ostatnie odkrycia pokazują, że jest to raczej patogen oportunistyczny niż specyficzny w folliculitis decalvans. Staphylococcus aureus kolonizujący folliculitis decalvans nie wydaje się bardziej zjadliwy niż izolowany z populacji ogólnej, jednak tylko częściowa odpowiedź na standardowe leczenie antybiotykami przeciwgronkowcowymi sugeruje raczej etiologię gram-ujemną ²⁶.

Terapia antybiotykowa może okazać się skuteczna w zmniejszeniu obciążenia bakteryjnego poniżej progu, który wyzwala układ odpornościowy, ale mikrobiota obecna w folliculitis decalvans po leczeniu antybiotykami nie jest całkowicie przywrócona do normy. Niezrównoważona mikrobiota z rezerwuarem bakterii komensalnych i oportunistycznych w mieszkach włosowych może podsycać niespecyficzne odpowiedzi układu odpornościowego, powodując przewlekły stan zapalny ²⁷.

Mechanizmy immunologiczne w zapaleniu mieszków włosowych

W patogenezie zapalenia mieszków włosowych istotną rolę odgrywają również mechanizmy immunologiczne:

Odpowiedź komórkowa – wyniki barwienia immunohistochemicznego wykazały, że limfocyty T pomocnicze przeważają w naciekach skórnych w przypadku demodekozy, co sugeruje możliwą rolę odpowiedzi immunologicznej komórkowej i opóźnionej nadwrażliwości ²⁸.
Odpowiedź humoralna – istnieją również dowody na komponent odpowiedzi immunologicznej humoralnej ze zwiększoną liczbą makrofagów i komórek Langerhansa w obecności zarażenia roztoczami Demodex ²⁹.
Oś IL-23/IL-17 – podobnie jak w przypadku innych zakażeń grzybiczych, takich jak te spowodowane przez dermatofity lub grzyby dimorficzne, oś IL-23/IL-17 jest kluczowa w pośredniczeniu w odpowiedzi immunologicznej przeciwko Malassezia ³⁰.
Inne receptory – inne receptory, takie jak IL-36R i receptor węglowodorowy arylowy (AhR), mogą być zaangażowane w rozpoznawanie Malassezia spp. przez keratynocyty, dalej wpływając na odpowiedź immunologiczną ³¹.

W przypadku zapalenia mieszków włosowych wywołanego przez Malassezia (MF) przypuszcza się, że pewne czynniki parakrynowe mogą wpływać na aktywację neutrofili, prowadząc do ich akumulacji w jednostce włosowo-łojowej i tworzenia krostek mieszkowych. Lipidy w hydrofobowej macierzy warstwy rogowej, a także wydzieliny gruczołów łojowych do mieszków włosowych, prawdopodobnie tworzą środowisko, które ułatwia agregację hydrofobowych grzybów ³².

Histopatologia zapalenia mieszków włosowych

Obraz histopatologiczny zapalenia mieszków włosowych zależy od etiologii i stopnia zaawansowania procesu chorobowego:

Powierzchowne zapalenie mieszków włosowych – charakteryzuje się obecnością komórek zapalnych w ujściu mieszka i górnych regionach mieszka. Naciek początkowo składa się z neutrofili, a później staje się bardziej mieszany z limfocytami i makrofagami ³³.
Głębokie zapalenie mieszków włosowych – naciek zapalny rozciąga się do głębszej części mieszka i skóry właściwej. Przewlekłe przypadki wykazują zapalenie ziarniniakowe z komórkami olbrzymimi zawierającymi keratynę i fragmenty włosów ³⁴.
Eozynofilowe zapalenie mieszków włosowych – histologicznie charakteryzuje się przewagą eozynofili w nacieku zapalnym obejmującym obszar okołomieszkowy i zewnętrzną osłonkę korzenia włosa, która wykazuje zmiany gąbczaste ³⁵.

Ropne zapalenie mieszków włosowych często goi się spontanicznie, niektóre długotrwałe przypadki mogą postępować do tworzenia się ziarniniaków lub zwłóknienia z widocznym klinicznie bliznowaceniem ³⁶.

Rola czynników środowiskowych

Różne czynniki środowiskowe mogą przyczyniać się do rozwoju zapalenia mieszków włosowych:

Pot i okluzja skóry – nadmierne pocenie się i okluzja skóry mogą potencjować zakażenie mieszków włosowych ³⁷.
Uraz i tarcie – uraz skóry, tarcie od ubrań lub intensywne pocieranie gąbką mogą ułatwić wniknięcie organizmów do skóry ³⁸.
Ekspozycja na zanieczyszczoną wodę – korzystanie z niechloorowanych lub nieodpowiednio utrzymanych wanien z hydromasażem, zjeżdżalni wodnych lub podgrzewanych basenów może prowadzić do zakażenia Pseudomonas aeruginosa ³⁹.
Usuwanie włosów – depilacja woskiem lub energiczne pocieranie gąbkami może ułatwić wniknięcie organizmów do skóry ⁴⁰.

Rola leków w patogenezie zapalenia mieszków włosowych

Niektóre leki mogą odgrywać rolę w patogenezie zapalenia mieszków włosowych:

Inhibitory receptora naskórkowego czynnika wzrostu (EGFR) – wydają się być istotne w zapaleniu mieszków włosowych poprzez powodowanie nieprawidłowego różnicowania naskórka, co prowadzi do zablokowania mieszka i następczego stanu zapalnego ⁴¹.
Długotrwałe stosowanie antybiotyków – może prowadzić do zapalenia mieszków włosowych gram-ujemnych, które powoduje krostki w miejscach trądziku na twarzy, szyi i górnej części tułowia ⁴².
Kortykosteroidy – mogą powodować trądzik steroidowy, formę zapalenia mieszków włosowych ⁴³.
Leki immunosupresyjne – mogą predysponować do rozwoju zapalenia mieszków włosowych poprzez tłumienie odpowiedzi immunologicznej ⁴⁴.

Mechanizmy molekularne w zapaleniu mieszków włosowych

Na poziomie molekularnym, w patogenezie zapalenia mieszków włosowych uczestniczą różne ścieżki sygnałowe i mediatory zapalenia:

Interakcja PGD2-CRTH2 – w eozynofilowym zapaleniu mieszków włosowych interakcja ta może być zaangażowana w patogenezę. Ponadto indometacyna może wywierać swój efekt terapeutyczny poprzez zmniejszenie ekspresji CRTH2, a także poprzez hamowanie syntezy PGD2 ⁴⁵.
Aktywność lipazy i fosfolipazy – w przypadku zapalenia mieszków włosowych wywołanego przez Malassezia, aktywność enzymatyczna lipazy i fosfolipazy drożdżaków może uszkadzać funkcję bariery skórnej i wywoływać podrażnienie ⁴⁶.
Receptory Toll-podobne – Malassezia może stymulować produkcję cytokin zapalnych przez keratynocyty za pośrednictwem receptora Toll-podobnego 2 i aktywować kaskady dopełniacza zarówno drogą klasyczną, jak i alternatywną ⁴⁷.
Przesunięcie w kierunku Th2 – sugeruje się, że przesunięcie w kierunku odpowiedzi immunologicznej typu T pomocniczego 2 (Th2) może być możliwym mechanizmem patogenetycznym odpowiedzialnym za infiltrację eozynofili w eozynofilowym zapaleniu mieszków włosowych ⁴⁸.

Mikrobiom skórny a zapalenie mieszków włosowych

Równowaga mikrobioty skórnej odgrywa istotną rolę w patogenezie zapalenia mieszków włosowych:

Dysbioza mikrobioty – w folliculitis decalvans dysbioza mikrobioty może stymulować nieprawidłową rekrutację komórek i załamać przywilej immunologiczny mieszka włosowego, eksponując neoanytgeny mieszkowe i promując nadmierną odpowiedź zapalną ⁴⁹.
Rola Cutibacterium acnes – ostatnie badania wykazały, że Cutibacterium acnes, powszechny komensalny organizm skórny, może indukować syntezę lipidów naskórka ⁵⁰.
Rola regulatorowych komórek T – regulatorowe komórki T odgrywają kluczową rolę w utrzymaniu integralności homeostatycznej mieszków łojowych, a także w ustanowieniu tolerancji immunologicznej na komensalne mikroby skórne ⁵¹.

W folliculitis decalvans antybiotykoterapia może okazać się skuteczna w zmniejszeniu obciążenia bakteryjnego poniżej progu, który wyzwala układ odpornościowy, ale mikrobiota obecna po leczeniu antybiotykami nie jest całkowicie przywrócona do normy. Niezrównoważona mikrobiota z rezerwuarem bakterii komensalnych i oportunistycznych w mieszkach włosowych może podsycać niespecyficzne odpowiedzi układu odpornościowego, powodując przewlekły stan zapalny ⁵².

Zespół okluzji mieszkowej

Zespół okluzji mieszkowej odnosi się do grupy schorzeń, które obejmują ⁵³:

Hidradenitis suppurativa (acne inversa) – przewlekły, nawracający, bolesny stan zapalny skóry w obszarach zawierających gruczoły apokrynowe. Niektórzy utrzymują, że choroba ta reprezentuje pierwotne zapalenie mieszków włosowych z wtórną okluzją gruczołów apokrynowych i ekrynowych ⁵⁴.
Acne conglobata – ciężka postać trądziku guzkowego-torbielowatego.
Dissecting cellulitis (perifolliculitis capitis abscedens et suffodiens) – przewlekłe, nawracające zapalenie skóry głowy charakteryzujące się tworzeniem się ropni i przetok.
Torbiel włosowa – stan zapalny w okolicy kości ogonowej.

Patogeneza hidradenitis suppurativa jest złożona. Badania sugerują, że proces jest przede wszystkim mieszkocentryczny z wtórnym zajęciem gruczołów apokrynowych, które opróżniają swoją zawartość do przewodu wyprowadzającego mieszka. Dane dotyczące patogenezy jako komórkowej odpowiedzi immunologicznej są mniej przekonujące ⁵⁵.

Podsumowanie mechanizmów patogenetycznych

Zapalenie mieszków włosowych ma złożoną patogenezę, która może obejmować różne mechanizmy:

Infekcyjne: bakteryjne (najczęściej Staphylococcus aureus), grzybicze (Malassezia), wirusowe (herpes simplex), pasożytnicze (Demodex).
Nieinfekcyjne: uraz mieszków włosowych, okluzja, reakcje polekowe.
Immunologiczne: reakcje nadwrażliwości, autoimmunizacja, dysregulacja odpowiedzi immunologicznej.
Środowiskowe: nadmierne pocenie się, ekspozycja na zanieczyszczoną wodę, stosowanie określonych kosmetyków i środków higienicznych.
Genetyczne: predyspozycje genetyczne mogą wpływać na strukturę i funkcję mieszków włosowych.

Zrozumienie złożonych mechanizmów patogenetycznych zapalenia mieszków włosowych jest kluczowe dla opracowania skutecznych strategii zapobiegania i leczenia tego powszechnego schorzenia skórnego ⁵⁶⁵⁷.

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Materiały źródłowe

#1 Infectious folliculitis – UpToDate
https://www.uptodate.com/contents/infectious-folliculitis
Folliculitis refers to inflammation of the superficial or deep portion of the hair follicle. The classic clinical findings of superficial folliculitis are folliculocentric, inflamed papules and/or pustules on hair-bearing skin. Nodules are a feature of deep, follicular inflammation. […] Folliculitis may be infectious or, less frequently, noninfectious. Various bacteria, fungi, viruses, and parasites are causes of infectious folliculitis, with bacteria as the most common cause. […] A correct diagnosis of infectious folliculitis is essential for appropriate management. The patient history and physical examination, particularly the assessment of the distribution of folliculitis, help to narrow the differential diagnosis. Detection of the causative organism confirms the diagnosis and may help direct therapy. […] The etiologies, clinical manifestations, diagnosis, and management of infectious folliculitis will be reviewed here. Noninfectious causes of folliculitis are reviewed separately.
#2 Folliculitis – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK547754/
Folliculitis is a common skin condition that usually involves infection of the hair follicle. While this condition is typically benign, prompt recognition can aid in the improvement of quality of life of patients with this condition. […] Most commonly, infection of the hair follicle is the mechanism behind most folliculitis cases. Even so, folliculitis may also result from fungal or viral infections, but this does not mean that all folliculitis cases are infectious. Sometimes, folliculitis may be the result of inflammation secondary to ingrown hairs as well as caused by certain drugs such as lithium and cyclosporine.
#3 Folliculitis – Wikipedia
https://en.wikipedia.org/wiki/Folliculitis
Folliculitis is the infection and inflammation of one or more hair follicles. The condition may occur anywhere on hair-covered skin. The rash may appear as pimples that come to white tips on the face, chest, back, arms, legs, buttocks, or head. […] Folliculitis starts with the introduction of a skin pathogen to a hair follicle. Hair follicles can also be damaged by friction from clothing, an insect bite, blockage of the follicle, shaving, or braids that are very tight and close to the scalp. The damaged follicles are then infected by Staphylococcus spp. […] Most carbuncles, boils, and other cases of folliculitis are infected with Staphylococcus aureus. […] Hot-tub folliculitis is caused by the bacterium Pseudomonas aeruginosa. The folliculitis usually occurs after sitting in a hot tub that was not properly cleaned before use.
#4 Folliculitis: Practice Essentials, Pathophysiology, Etiology
https://emedicine.medscape.com/article/1070456-overview
Folliculitis refers to inflammation of the hair follicle and is classified based upon which anatomic level of the hair follicle (superficial or deep) is involved; however, this distinction is not always clear cut. Folliculitis can also be subdivided into infective (bacterial, viral, fungal, or parasitic) and non-infectious etiologies with the latter most commonly arising due to follicular trauma, inflammation, occlusion or drug induced. […] Eosinophilic folliculitis is a subtype of non-infectious folliculitides hypothesized to occur as a result of an autoimmune process directed against the sebocytes or some component of the sebum. […] Although classically acne was classified as a follicular occlusive disorder, recently there has been a paradigm shift, and it is now felt to represent a primary inflammatory disorder of the pilosebaceous unit given that perifollicular inflammatory cells can be seen in the earliest stages of development prior to the appearance of the microcomedone. Hyperkeratinization then results in follicular obstruction, which allows for sebum accumulation resulting in further distension of the follicle. The normally commensal bacteria (Cutibacterium acnes formerly Propionibacterium acnes) forms a biofilm and its lipases break down sebum triglycerides into proinflammatory fatty acids and activate the innate immune response through toll-like receptor-2.
#5 FOLLICULITIS.ppt
https://www.slideshare.net/slideshow/folliculitisppt/257713218
Folliculitis is a common skin infection of hair follicles, usually caused by Staphylococcus aureus bacteria. It presents as inflamed bumps with hairs protruding from the center. […] Folliculitis Pathogenesis Staphylococci gain entry into the follicles through the follicular orifice establish low-grade infection within the epidermis surrounding the follicular canal forming a pustule(small blister or pimple on skin containing pus) Patients who carry staphylococcus in their nose and skin are more susceptible. […] Folliculitis is a superficial infection and inflammation of at the mouth of the hair follicle Is secondary to infection by Staphylococcus aureus. Other aetiological causes include staphylococcus group A, Escherichia coli or gram-negative organisms in individuals with acne on antibiotic treatment or people exposed to hot swimming pools contaminated with Pseudomonas aeruginosa. Lesions of folliculitis are usually seen on hairy parts of the body.
#6 Bacterial Folliculitis â DermNet
https://dermnetnz.org/topics/bacterial-folliculitis
Folliculitis is inflammation of the hair follicle due to infection, chemical irritation or physical injury. Bacterial folliculitis is usually due to Staphylococcus aureus. Less often, coagulase-negative staphylococci and gram-negative organisms are responsible including anaerobes. Spa pool folliculitis is caused by Pseudomonas. Bacterial folliculitis can lead to cellulitis and lymphangitis; subsequent bacteraemia might result in osteomyelitis, septic arthritis or pneumonia. Bacterial folliculitis is usually diagnosed clinically but can be confirmed by bacterial swabs sent for microscopy, culture and sensitivity. Skin biopsy is rarely necessary. Histology shows dense neutrophilic infiltrate in the subcutaneous tissue and foreign body reaction around a hair shaft. […] The infection with Gram-negative organisms causes pustules in acne sites of the face, neck and upper trunk.
#7 Pseudomonas Folliculitis: Background, Pathophysiology, Etiology
https://emedicine.medscape.com/article/1053170-overview
Pseudomonas folliculitis is a community-acquired skin infection that results from bacterial colonization of hair follicles after exposure to contained contaminated water. Pseudomonas is one of the top three pathogens associated with recreational water use. First reported in 1975 in association with whirlpool contamination, Pseudomonas folliculitis is caused by strains of Pseudomonas aeruginosa that are acquired secondary to skin contamination. […] The ubiquitous gram-negative bacterial organism P aeruginosa, found in soil and fresh water, gains entry through hair follicles or via breaks in the skin. Bacterial serotype O:11 is the most commonly reported isolate for water-associated Pseudomonas folliculitis, but other serotypes that have been reported include O:1, O:3, O:4, O:6, O:7, O:9, O:10, and O:16. Serotype O:11 is possibly more invasive or better adapted to survive in halogenated water. […] Minor trauma from wax depilation or vigorous rubbing with sponges may facilitate the entry of organisms into the skin, and a dose-response relation exists with respect to the degree of water contamination. Hot water, high pH (7.8), and low chlorine level (0.5 mg/L) all predispose to infection.
#8 Malassezia Folliculitis: Pathogenesis and Diagnostic Challenges
https://pmc.ncbi.nlm.nih.gov/articles/PMC11633069/
Malassezia folliculitis (MF) is a fungal infection that often presents with pruritic follicular papules and pustules, primarily affecting the upper body. […] This case emphasizes the importance of considering fungal etiologies in folliculitis, particularly in patients with recurrent or treatment-resistant symptoms. […] Managing MF poses a clinical challenge due to its similarity to other forms of folliculitis, particularly bacterial folliculitis and acneiform eruptions. […] Correctly distinguishing MF from other forms of folliculitis is crucial to initiating appropriate antifungal therapy. […] Malassezia spp. species are lipophilic, thriving in seborrheic areas like the scalp and trunk due to their dependence on external long-chain fatty acids for energy and structural components, as they cannot synthesize these on their own.
#9 Folliculitis
https://dermnetnz.org/topics/folliculitis
Folliculitis means an inflamed hair follicle due to any cause. The result is a tender red spot, often with a surface pustule. […] Folliculitis can be due to infection, occlusion (blockage), irritation and various skin diseases. […] Swabs should be taken from the pustules for cytology and culture in the laboratory to determine if folliculitis is due to an infection. […] Bacterial folliculitis is commonly due to Staphylococcus aureus. If the infection involves the deep part of the follicle, it results in a painful boil. […] Spa pool folliculitis is due to infection with Pseudomonas aeruginosa, which thrives in warm water. […] The most common yeast to cause a folliculitis is Pityrosporum ovale, also known as Malassezia. […] Folliculitis may arise as hairs regrow after shaving, waxing, electrolysis, or plucking.
#10 Folliculitis – Wikipedia
https://en.wikipedia.org/wiki/Folliculitis
Sycosis vulgaris, sycosis barbae, or barber’s itch is a staphylococcal infection of the hair follicles in the bearded area of the face, usually the upper lip. Shaving aggravates the condition. […] Gram-negative folliculitis may appear after prolonged acne treatment with antibiotics. […] Demodex folliculitis is usually caused by an overgrowth of Demodex folliculorum, a mite that lives in human hair follicles. […] Herpetic folliculitis is rarer, but may occur when herpes simplex virus infection spreads to nearby hair follicles appearing in groups or clusters, mostly around the mouth. […] Folliculitis decalvans or tufted folliculitis usually affects the scalp. Several hairs arise from the same hair follicle. Scarring and permanent hair loss may follow. The cause is unknown.
#11 Folliculitis – Wikipedia
https://en.wikipedia.org/wiki/Folliculitis
Sycosis vulgaris, sycosis barbae, or barber’s itch is a staphylococcal infection of the hair follicles in the bearded area of the face, usually the upper lip. Shaving aggravates the condition. […] Gram-negative folliculitis may appear after prolonged acne treatment with antibiotics. […] Demodex folliculitis is usually caused by an overgrowth of Demodex folliculorum, a mite that lives in human hair follicles. […] Herpetic folliculitis is rarer, but may occur when herpes simplex virus infection spreads to nearby hair follicles appearing in groups or clusters, mostly around the mouth. […] Folliculitis decalvans or tufted folliculitis usually affects the scalp. Several hairs arise from the same hair follicle. Scarring and permanent hair loss may follow. The cause is unknown.
#12 Folliculitis – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK547754/
Folliculitis is a common skin condition that usually involves infection of the hair follicle. While this condition is typically benign, prompt recognition can aid in the improvement of quality of life of patients with this condition. […] Most commonly, infection of the hair follicle is the mechanism behind most folliculitis cases. Even so, folliculitis may also result from fungal or viral infections, but this does not mean that all folliculitis cases are infectious. Sometimes, folliculitis may be the result of inflammation secondary to ingrown hairs as well as caused by certain drugs such as lithium and cyclosporine.
#13 Folliculitis
https://dermnetnz.org/topics/folliculitis
Folliculitis means an inflamed hair follicle due to any cause. The result is a tender red spot, often with a surface pustule. […] Folliculitis can be due to infection, occlusion (blockage), irritation and various skin diseases. […] Swabs should be taken from the pustules for cytology and culture in the laboratory to determine if folliculitis is due to an infection. […] Bacterial folliculitis is commonly due to Staphylococcus aureus. If the infection involves the deep part of the follicle, it results in a painful boil. […] Spa pool folliculitis is due to infection with Pseudomonas aeruginosa, which thrives in warm water. […] The most common yeast to cause a folliculitis is Pityrosporum ovale, also known as Malassezia. […] Folliculitis may arise as hairs regrow after shaving, waxing, electrolysis, or plucking.
#14 FOLLICULITIS.ppt
https://www.slideshare.net/slideshow/folliculitisppt/257713218
Folliculitis is a common skin infection of hair follicles, usually caused by Staphylococcus aureus bacteria. It presents as inflamed bumps with hairs protruding from the center. […] Folliculitis Pathogenesis Staphylococci gain entry into the follicles through the follicular orifice establish low-grade infection within the epidermis surrounding the follicular canal forming a pustule(small blister or pimple on skin containing pus) Patients who carry staphylococcus in their nose and skin are more susceptible. […] Folliculitis is a superficial infection and inflammation of at the mouth of the hair follicle Is secondary to infection by Staphylococcus aureus. Other aetiological causes include staphylococcus group A, Escherichia coli or gram-negative organisms in individuals with acne on antibiotic treatment or people exposed to hot swimming pools contaminated with Pseudomonas aeruginosa. Lesions of folliculitis are usually seen on hairy parts of the body.
#15 Folliculitis
https://dermnetnz.org/topics/folliculitis
Eosinophilic folliculitis is a specific type of folliculitis that may arise in some immune-suppressed individuals such as those infected by human immunodeficiency virus (HIV) or those who have cancer. […] Folliculitis may be due to drugs, particularly corticosteroids (steroid acne), androgens (male hormones), adrenocorticotrophic hormone (ACTH), lithium, isoniazid (INH), phenytoin and B-complex vitamins. […] Certain uncommon inflammatory skin diseases may cause permanent hair loss and scarring because of deep-seated sterile folliculitis. […] The follicular occlusion syndrome refers to: Hidradenitis suppurativa (acne inversa), Acne conglobata (a severe form of nodulocystic acne), Dissecting cellulitis (perifolliculitis capitis abscedens et suffodiens), Pilonidal sinus. […] Folliculitis affecting the buttocks is quite common in males and females.
#16 Folliculitis: Practice Essentials, Pathophysiology, Etiology
https://emedicine.medscape.com/article/1070456-overview
Folliculitis refers to inflammation of the hair follicle and is classified based upon which anatomic level of the hair follicle (superficial or deep) is involved; however, this distinction is not always clear cut. Folliculitis can also be subdivided into infective (bacterial, viral, fungal, or parasitic) and non-infectious etiologies with the latter most commonly arising due to follicular trauma, inflammation, occlusion or drug induced. […] Eosinophilic folliculitis is a subtype of non-infectious folliculitides hypothesized to occur as a result of an autoimmune process directed against the sebocytes or some component of the sebum. […] Although classically acne was classified as a follicular occlusive disorder, recently there has been a paradigm shift, and it is now felt to represent a primary inflammatory disorder of the pilosebaceous unit given that perifollicular inflammatory cells can be seen in the earliest stages of development prior to the appearance of the microcomedone. Hyperkeratinization then results in follicular obstruction, which allows for sebum accumulation resulting in further distension of the follicle. The normally commensal bacteria (Cutibacterium acnes formerly Propionibacterium acnes) forms a biofilm and its lipases break down sebum triglycerides into proinflammatory fatty acids and activate the innate immune response through toll-like receptor-2.
#17 Folliculitis
https://dermnetnz.org/topics/folliculitis
Eosinophilic folliculitis is a specific type of folliculitis that may arise in some immune-suppressed individuals such as those infected by human immunodeficiency virus (HIV) or those who have cancer. […] Folliculitis may be due to drugs, particularly corticosteroids (steroid acne), androgens (male hormones), adrenocorticotrophic hormone (ACTH), lithium, isoniazid (INH), phenytoin and B-complex vitamins. […] Certain uncommon inflammatory skin diseases may cause permanent hair loss and scarring because of deep-seated sterile folliculitis. […] The follicular occlusion syndrome refers to: Hidradenitis suppurativa (acne inversa), Acne conglobata (a severe form of nodulocystic acne), Dissecting cellulitis (perifolliculitis capitis abscedens et suffodiens), Pilonidal sinus. […] Folliculitis affecting the buttocks is quite common in males and females.
#18 Eosinophilic folliculitis – Therapeutics in Dermatology
https://www.therapeutique-dermatologique.org/spip.php?article1558
Eosinophilic folliculitis is a noninfectious follicular disorder mediated by eosinophils. Its etiology is unknown, although it has been suggested that a T-helper type 2 (Th2) shift may be a possible pathogenic mechanism for the infiltration of eosinophils. […] Histologically, eosinophils predominate in the inflammatory infiltrate involving the perifollicular area and the hair follicle outer rooth sheat which displays spongiotic change. A perivascular and interstitial infiltrate with admixed lymphocytes and eosinophils is often present as well, with negative special stains for microorganisms. Ofujis disease and Eosinophilic pustular folliculitis of infancy are also characterized by the frequent occurrence of epidermal changes with eosinophils exocytosis and spongiosis resulting in small subcorneal or intraepidermal eosinophilic pustules.
#19 Pathological analysis of eosinophilic pustular folliculitis | CCID
https://www.dovepress.com/clinical-and-pathological-analysis-of-10-cases-of-eosinophilic-pustula-peer-reviewed-fulltext-article-CCID
Eosinophilic pustular folliculitis (EPF), known as Ofujis disease (OD), was initially identified and documented by Japanese scholar Ofuji in 1970. This cutaneous follicular disease is of uncertain origin. EPF is a relatively uncommon dermatosis characterized by chronicity, pruritus, and septicity. Its aetiology remains unclear, currently categorized as a non-specific reaction. The condition is chronic, commonly affecting young adult males. EPF is generally classified into three types: classic EPF (C-EPF), immunosuppression-associated EPF (IS-EPF), and infantile EPF (I-EPF), of which C-EPF is the most common type. The pathogenesis is unknown, but it may be a non-specific response to various antigenic stimuli that impair the immune system. The classic EPF lesions appear as follicular papular pustules on an erythematous base, 1 to 2 mm in diameter, and extend eccentrically around in a circular or creeping pattern for 7 to 10 days, alternating between self-remission and exacerbation, and recurring once every 3 to 4 weeks. Typical histology of EPF: In the early stages of pustule formation, sponge formation due to fragmentation and degeneration of epithelial cells or small blister formation in the outer hair root sheath with eosinophilic leukocytes and some mononuclear cell infiltration. In the progressive stage, longitudinal blisters appear in the outer hair root sheaths with many eosinophilic leukocytes mixed with mononuclear cells, polymorphonuclear leukocytes, and epithelial cells. Lymphocytes and histiocytes with eosinophilic leukocytes also infiltrate around the vessels and hair follicles. In terms of pathogenesis, the activity of the sebaceous glands had been suspected as a cause of eosinophilic leukocyte accumulation in the hair follicles because the preference is limited to the sebaceous area, and many cases have a history of common acne. It has been found that 40% of patients with EPF have mucin deposits around the hair follicles and sebaceous glands. The cause of mucin production is not yet clear. Still, it has been suggested that follicular damage may be due to an increase in eosinophilic leukocytes in the blood, which is nonspecifically recruited into the sebaceous follicles by chemotactic substances and mixed with neutrophils, which in turn cause fragmentation of the follicular epithelium and the formation of small abscesses and mucinosis-like changes. Pruritus was a common symptom reported by patients, and eosinophilia was increased in varying degrees, but not in all patients, probably related to the onset and time of consultation, indicating that eosinophilia is not a constant feature. Many therapeutic agents have been used for EPF, including topical and oral corticosteroids, antibiotics such as minocycline, isotretinoin, ultraviolet (UV)B phototherapy, and interferon therapy, but no specific treatment is available. However, there are no specific drugs for the treatment of this disease.
#20 Folliculitis – Wikipedia
https://en.wikipedia.org/wiki/Folliculitis
Sycosis vulgaris, sycosis barbae, or barber’s itch is a staphylococcal infection of the hair follicles in the bearded area of the face, usually the upper lip. Shaving aggravates the condition. […] Gram-negative folliculitis may appear after prolonged acne treatment with antibiotics. […] Demodex folliculitis is usually caused by an overgrowth of Demodex folliculorum, a mite that lives in human hair follicles. […] Herpetic folliculitis is rarer, but may occur when herpes simplex virus infection spreads to nearby hair follicles appearing in groups or clusters, mostly around the mouth. […] Folliculitis decalvans or tufted folliculitis usually affects the scalp. Several hairs arise from the same hair follicle. Scarring and permanent hair loss may follow. The cause is unknown.
#21 Pseudofolliculitis Barbae: Prevention and Treatment
https://www.uspharmacist.com/article/pseudofolliculitis-barbae-prevention-and-treatment
The pathogenesis of PFB is thought to be multifactorial. However, transfollicular penetration and extrafollicular penetration have been identified as the two primary processes responsible for the initial development of the PFB lesion. Transfollicular penetration occurs when the hair tip fails to exit through the epidermal layer and instead curves downward and continues to grow, eventually piercing the dermis, which causes an inflammatory reaction. Pulling the skin taut while shaving, using tweezers to pluck hair, and shaving with multiple-blade razors that leave the resultant hair tip in the follicle below the skins surface can lead to transfollicular penetration. Extrafollicular penetration is likely to develop after the use of a single-blade razor that cuts the hair shaft at the surface of the epidermis. The freshly cut hair, now with a sharpened tip, curls back into the epidermis a short distance away from the follicle and continues to grow downward, penetrating the epidermal layer. Similar to what takes place with transfollicular penetration, a foreign-body inflammatory reaction ensues, causing pain, inflammation, and the classic PFB lesion.
#22 Pseudofolliculitis Barbae: Prevention and Treatment
https://www.uspharmacist.com/article/pseudofolliculitis-barbae-prevention-and-treatment
The pathogenesis of PFB is thought to be multifactorial. However, transfollicular penetration and extrafollicular penetration have been identified as the two primary processes responsible for the initial development of the PFB lesion. Transfollicular penetration occurs when the hair tip fails to exit through the epidermal layer and instead curves downward and continues to grow, eventually piercing the dermis, which causes an inflammatory reaction. Pulling the skin taut while shaving, using tweezers to pluck hair, and shaving with multiple-blade razors that leave the resultant hair tip in the follicle below the skins surface can lead to transfollicular penetration. Extrafollicular penetration is likely to develop after the use of a single-blade razor that cuts the hair shaft at the surface of the epidermis. The freshly cut hair, now with a sharpened tip, curls back into the epidermis a short distance away from the follicle and continues to grow downward, penetrating the epidermal layer. Similar to what takes place with transfollicular penetration, a foreign-body inflammatory reaction ensues, causing pain, inflammation, and the classic PFB lesion.
#23 Pseudofolliculitis barbae – Wikipedia
https://en.wikipedia.org/wiki/Pseudofolliculitis_barbae
Pseudofolliculitis barbae (PFB) is a type of irritant folliculitis that commonly affects people who have curly or thick facial hair. It occurs when hair curls back into the skin after shaving, causing inflammation, redness, and bumps. This can lead to ingrown hairs, scarring, and skin discoloration. […] Pseudofolliculitis barbae can further be divided into two types of ingrown hairs: transfollicular and extrafollicular. The extrafollicular hair is a hair that has exited the follicle and reentered the skin. The transfollicular hair never exits the follicle, but because of its naturally curly nature curls back into the follicle, causing fluid build-up and irritation. […] A common polymorphism in a keratin gene (K6hf) has been linked to PFB, suggesting that it may be a genetic risk factor. This sequence change leads to an amino acid substitution in the highly conserved helix initiation motif of the K6hf rod domain. Carriers of the A12T polymorphism are six times more likely to develop PFB compared with people homozygous for the wild-type K6hf sequence. This suggests K6hf mutation structurally weakens the companion layer separating the inner and outer root sheath and increases the chances that a beard hair will in-grow. […] The mechanism of action of glycolic acid is unknown, but it is hypothesized that straighter hair growth is caused by the reduction of sulfhydryl bonds in the hair shaft by glycolic acid, which results in reduced re-entry of the hair shaft into the follicular wall or epidermis.
#24 Russian Journal of Skin and Venereal Diseases
https://rjsvd.com/1560-9588/
Folliculitis decalvans is a rare neutrophilic cicatricial alopecia of the scalp. As it is a progressive inflammatory disease characterized by a gradual increase in the area of inflamed follicles with the formation of areas of cicatricial alopecia in the outcome. […] The exact cause of folliculitis decalvans is not fully understood, but it is believed that Staphylococcus aureus may play a role in its development. Current knowledge regarding the pathogenesis of folliculitis decalvans suggests three stages including hyperactivation of innate immunity, bacterial infection and fibrosis as an outcome of the disease. […] The combination of ultraviolet-B 308 nm, oral antibiotics, topical combined glucocorticoid drugs, topical and systemic application of bacteriophages, sensitives to the identified flora to the drugs have demonstrated an excellent tolerance and great outcomes in a series of cases.
#25 Russian Journal of Skin and Venereal Diseases
https://rjsvd.com/1560-9588/
Folliculitis decalvans is a rare neutrophilic cicatricial alopecia of the scalp. As it is a progressive inflammatory disease characterized by a gradual increase in the area of inflamed follicles with the formation of areas of cicatricial alopecia in the outcome. […] The exact cause of folliculitis decalvans is not fully understood, but it is believed that Staphylococcus aureus may play a role in its development. Current knowledge regarding the pathogenesis of folliculitis decalvans suggests three stages including hyperactivation of innate immunity, bacterial infection and fibrosis as an outcome of the disease. […] The combination of ultraviolet-B 308 nm, oral antibiotics, topical combined glucocorticoid drugs, topical and systemic application of bacteriophages, sensitives to the identified flora to the drugs have demonstrated an excellent tolerance and great outcomes in a series of cases.
#26 Role of Staphylococcus aureus in the pathogenesis of folliculitis decalvans | Jedlecka | Forum Dermatologicum
https://journals.viamedica.pl/forum_dermatologicum/article/view/87879
Folliculitis decalvans (FD) is an inflammatory cicatricial alopecia. Its aetiology remains unclear but an imbalance of skin microbiota seems to play a special role in the pathogenesis. […] Previously Staphylococcus aureus (S. aureus) was postulated to play the main role in the pathogenesis of the disease, but recent findings show it is rather opportunistic than a specific pathogen in FD. Staphylococcus aureus colonizing FD does not seem to be more virulent than one isolated from the general population, however, only a partial response to standard anti-staphylococcal antibiotic treatment suggests rather gram-negative aetiology. Antibiotic therapy may prove effective to reduce bacterial load below the threshold that triggers the immune system, but the microbiota found in FD after antibiotic treatment is not entirely restored to normal. Unbalanced microbiota with the reservoir of commensal and opportunistic bacteria in hair follicles may stoke unspecific responses of the immune system, therefore causing chronic inflammation.
#27 Role of Staphylococcus aureus in the pathogenesis of folliculitis decalvans | Jedlecka | Forum Dermatologicum
https://journals.viamedica.pl/forum_dermatologicum/article/view/87879
Folliculitis decalvans (FD) is an inflammatory cicatricial alopecia. Its aetiology remains unclear but an imbalance of skin microbiota seems to play a special role in the pathogenesis. […] Previously Staphylococcus aureus (S. aureus) was postulated to play the main role in the pathogenesis of the disease, but recent findings show it is rather opportunistic than a specific pathogen in FD. Staphylococcus aureus colonizing FD does not seem to be more virulent than one isolated from the general population, however, only a partial response to standard anti-staphylococcal antibiotic treatment suggests rather gram-negative aetiology. Antibiotic therapy may prove effective to reduce bacterial load below the threshold that triggers the immune system, but the microbiota found in FD after antibiotic treatment is not entirely restored to normal. Unbalanced microbiota with the reservoir of commensal and opportunistic bacteria in hair follicles may stoke unspecific responses of the immune system, therefore causing chronic inflammation.
#28 Resistant Scalp Folliculitis Secondary to Demodex Infestation | MDedge Dermatology
https://www.mdedge9-ma1.mdedge.com/dermatology/article/67298/hair-nails/resistant-scalp-folliculitis-secondary-demodex-infestation
Results of immunohistochemical staining have shown that helper T lymphocytes predominate in the dermal infiltrate of demodicosis suggesting a possible role of cell-mediated immune response and delayed hypersensitivity. […] There also is evidence for a humoral immune response component with increased macrophages and Langerhans cells in the presence of infestation with Demodex. […] Demodex mites have been implicated as a causative agent in rosacea and pustular folliculitis. […] It is important to consider the possibility that the vascular changes of rosacea create an environment that is favorable to the multiplication of Demodex mites and their penetration into the dermis. […] Forton and Seys reported that Demodex mites are associated with the inflammatory symptoms of rosacea and that the mites are present in greater numbers and higher frequencies in patients with rosacea.
#29 Resistant Scalp Folliculitis Secondary to Demodex Infestation | MDedge Dermatology
https://www.mdedge9-ma1.mdedge.com/dermatology/article/67298/hair-nails/resistant-scalp-folliculitis-secondary-demodex-infestation
Results of immunohistochemical staining have shown that helper T lymphocytes predominate in the dermal infiltrate of demodicosis suggesting a possible role of cell-mediated immune response and delayed hypersensitivity. […] There also is evidence for a humoral immune response component with increased macrophages and Langerhans cells in the presence of infestation with Demodex. […] Demodex mites have been implicated as a causative agent in rosacea and pustular folliculitis. […] It is important to consider the possibility that the vascular changes of rosacea create an environment that is favorable to the multiplication of Demodex mites and their penetration into the dermis. […] Forton and Seys reported that Demodex mites are associated with the inflammatory symptoms of rosacea and that the mites are present in greater numbers and higher frequencies in patients with rosacea.
#30 Malassezia Folliculitis: Pathogenesis and Diagnostic Challenges
https://pmc.ncbi.nlm.nih.gov/articles/PMC11633069/
Recent research has demonstrated that Cutibacterium acnes, a common skin commensal, can induce epidermal lipid synthesis. […] In MF, it is hypothesized that certain paracrine factors may influence neutrophil activation, leading to their accumulation in the pilosebaceous unit and the formation of follicular pustules. […] The lipids in the hydrophobic matrix of the stratum corneum, as well as sebaceous gland secretions into the hair follicles, likely create an environment that facilitates the aggregation of hydrophobic fungi. […] As with other fungal infections, such as those caused by dermatophytes or dimorphic fungi, the IL-23/IL-17 axis is crucial in mediating the immune response against Malassezia. […] Other receptors, like IL-36R and the aryl hydrocarbon receptor (AhR), may be involved in keratinocyte recognition of Malassezia spp., further influencing the immune response.
#31 Malassezia Folliculitis: Pathogenesis and Diagnostic Challenges
https://pmc.ncbi.nlm.nih.gov/articles/PMC11633069/
Recent research has demonstrated that Cutibacterium acnes, a common skin commensal, can induce epidermal lipid synthesis. […] In MF, it is hypothesized that certain paracrine factors may influence neutrophil activation, leading to their accumulation in the pilosebaceous unit and the formation of follicular pustules. […] The lipids in the hydrophobic matrix of the stratum corneum, as well as sebaceous gland secretions into the hair follicles, likely create an environment that facilitates the aggregation of hydrophobic fungi. […] As with other fungal infections, such as those caused by dermatophytes or dimorphic fungi, the IL-23/IL-17 axis is crucial in mediating the immune response against Malassezia. […] Other receptors, like IL-36R and the aryl hydrocarbon receptor (AhR), may be involved in keratinocyte recognition of Malassezia spp., further influencing the immune response.
#32 Malassezia Folliculitis: Pathogenesis and Diagnostic Challenges
https://pmc.ncbi.nlm.nih.gov/articles/PMC11633069/
Recent research has demonstrated that Cutibacterium acnes, a common skin commensal, can induce epidermal lipid synthesis. […] In MF, it is hypothesized that certain paracrine factors may influence neutrophil activation, leading to their accumulation in the pilosebaceous unit and the formation of follicular pustules. […] The lipids in the hydrophobic matrix of the stratum corneum, as well as sebaceous gland secretions into the hair follicles, likely create an environment that facilitates the aggregation of hydrophobic fungi. […] As with other fungal infections, such as those caused by dermatophytes or dimorphic fungi, the IL-23/IL-17 axis is crucial in mediating the immune response against Malassezia. […] Other receptors, like IL-36R and the aryl hydrocarbon receptor (AhR), may be involved in keratinocyte recognition of Malassezia spp., further influencing the immune response.
#33 Pathology Outlines – Folliculitis
https://www.pathologyoutlines.com/topic/skinnontumorfolliculitis.html
Primary inflammation of a hair follicle, either infectious or noninfectious […] Caused by infection, friction and other causes of follicular trauma, excessive perspiration and occlusion […] Infectious cases are either superficial (fungi, bacteria, syphilis, viral) or deep (usually granulomatous and due to either fungi or bacteria) […] Epidermal growth factor receptor (EGFR) inhibitors appear to be relevant in folliculitis by causing abnormal epidermal differentiation that leads to follicular obstruction and subsequent inflammation (Br J Dermatol 2001;144:1169) […] Superficial folliculitis has moderate inflammatory cells in the follicular ostium and upper regions of the follicle […] Infiltrate initially consists of neutrophils, later becomes more mixed with lymphocytes and macrophages.
#34 Folliculitis – wikidoc
https://www.wikidoc.org/index.php/Folliculitis
The pathogenesis of folliculitis depends upon the etiological agent. It can be caused by an infection (bacterial, viral, fungal, or parasitic) or have a noninfectious etiology, as the result of follicular trauma, inflammation, occlusion, scratch around the hair follicle or topical application of steroids may induce the infection and subsequently inflammation of the hair follicle. […] Although the cause of Esinophilic Folliculitis is unknown. A variety of microorganisms have been implicated, including the mite Demodex, the yeast Pityrosporum, and bacteria. An autoimmune process has also been investigated. […] On microscopic pathology, superficial folliculitis characterized by neutrophic infiltration confined to the infundibulum of the hair follicle, however in deep folliculitis it extend to the deeper portion of the follicle and dermis. Infiltrate initially consists of neutrophils, later becomes mixed with lymphocytes and macrophages. Chronic cases shows granulomatous inflammation with giant cells containing keratin and fragmented hair. Suppurative folliculitiis often heals spontaneously, some longstanding cases may progress to the formation of granulomas or fibrosis with evident clinical scarring.
#35 Eosinophilic folliculitis – Therapeutics in Dermatology
https://www.therapeutique-dermatologique.org/spip.php?article1558
Eosinophilic folliculitis is a noninfectious follicular disorder mediated by eosinophils. Its etiology is unknown, although it has been suggested that a T-helper type 2 (Th2) shift may be a possible pathogenic mechanism for the infiltration of eosinophils. […] Histologically, eosinophils predominate in the inflammatory infiltrate involving the perifollicular area and the hair follicle outer rooth sheat which displays spongiotic change. A perivascular and interstitial infiltrate with admixed lymphocytes and eosinophils is often present as well, with negative special stains for microorganisms. Ofujis disease and Eosinophilic pustular folliculitis of infancy are also characterized by the frequent occurrence of epidermal changes with eosinophils exocytosis and spongiosis resulting in small subcorneal or intraepidermal eosinophilic pustules.
#36 Folliculitis – wikidoc
https://www.wikidoc.org/index.php/Folliculitis
The pathogenesis of folliculitis depends upon the etiological agent. It can be caused by an infection (bacterial, viral, fungal, or parasitic) or have a noninfectious etiology, as the result of follicular trauma, inflammation, occlusion, scratch around the hair follicle or topical application of steroids may induce the infection and subsequently inflammation of the hair follicle. […] Although the cause of Esinophilic Folliculitis is unknown. A variety of microorganisms have been implicated, including the mite Demodex, the yeast Pityrosporum, and bacteria. An autoimmune process has also been investigated. […] On microscopic pathology, superficial folliculitis characterized by neutrophic infiltration confined to the infundibulum of the hair follicle, however in deep folliculitis it extend to the deeper portion of the follicle and dermis. Infiltrate initially consists of neutrophils, later becomes mixed with lymphocytes and macrophages. Chronic cases shows granulomatous inflammation with giant cells containing keratin and fragmented hair. Suppurative folliculitiis often heals spontaneously, some longstanding cases may progress to the formation of granulomas or fibrosis with evident clinical scarring.
#37 Folliculitis – Dermatologic Disorders – Merck Manual Professional Edition
https://www.merckmanuals.com/professional/dermatologic-disorders/bacterial-skin-infections/folliculitis
Folliculitis is an infection of hair follicles. […] The etiology of folliculitis is often unclear, but perspiration, trauma, friction, and occlusion of the skin are known to potentiate infection. The pathogen may be bacterial, fungal, viral, or parasitic. […] Bacterial folliculitis is usually caused by Staphylococcus aureus, but occasionally Pseudomonas aeruginosa (hot tub folliculitis) or other organisms have been reported. […] Folliculitis can be caused by various pathogens and tends to be potentiated by perspiration, trauma, friction, and occlusion of the skin. […] Bacterial folliculitis is usually caused by Staphylococcus aureus but occasionally Pseudomonas aeruginosa (hot tub folliculitis).
#38 Pseudomonas Folliculitis: Background, Pathophysiology, Etiology
https://emedicine.medscape.com/article/1053170-overview
Pseudomonas folliculitis is a community-acquired skin infection that results from bacterial colonization of hair follicles after exposure to contained contaminated water. Pseudomonas is one of the top three pathogens associated with recreational water use. First reported in 1975 in association with whirlpool contamination, Pseudomonas folliculitis is caused by strains of Pseudomonas aeruginosa that are acquired secondary to skin contamination. […] The ubiquitous gram-negative bacterial organism P aeruginosa, found in soil and fresh water, gains entry through hair follicles or via breaks in the skin. Bacterial serotype O:11 is the most commonly reported isolate for water-associated Pseudomonas folliculitis, but other serotypes that have been reported include O:1, O:3, O:4, O:6, O:7, O:9, O:10, and O:16. Serotype O:11 is possibly more invasive or better adapted to survive in halogenated water. […] Minor trauma from wax depilation or vigorous rubbing with sponges may facilitate the entry of organisms into the skin, and a dose-response relation exists with respect to the degree of water contamination. Hot water, high pH (7.8), and low chlorine level (0.5 mg/L) all predispose to infection.
#39 Folliculitis – Symptoms & causes – Mayo Clinic
https://www.mayoclinic.org/diseases-conditions/folliculitis/symptoms-causes/syc-20361634
Hot tub rash (pseudomonas folliculitis). This type is a rash of round, itchy bumps that can show up 1 to 2 days after exposure to the bacteria that causes it. Hot tub folliculitis is caused by pseudomonas bacteria, which can be found in hot tubs, water slides and heated pools in which the chlorine and pH levels aren’t correct. […] Razor bumps (pseudofolliculitis barbae). This rash can look like folliculitis but it’s caused by ingrown hairs, not infected follicles. It mainly affects people with curly hair who shave too close and is most noticeable on the face and neck. […] Pityrosporum (pit-ih-ROS-puh-rum) folliculitis. This type is a rash of itchy, pus-filled bumps, most often on the back and chest. It’s caused by a yeast infection. […] Gram-negative folliculitis. This type causes pus-filled bumps around the nose and mouth. It sometimes develops in people who are receiving long-term antibiotic therapy for acne.
#40 Pseudomonas Folliculitis: Background, Pathophysiology, Etiology
https://emedicine.medscape.com/article/1053170-overview
Pseudomonas folliculitis is a community-acquired skin infection that results from bacterial colonization of hair follicles after exposure to contained contaminated water. Pseudomonas is one of the top three pathogens associated with recreational water use. First reported in 1975 in association with whirlpool contamination, Pseudomonas folliculitis is caused by strains of Pseudomonas aeruginosa that are acquired secondary to skin contamination. […] The ubiquitous gram-negative bacterial organism P aeruginosa, found in soil and fresh water, gains entry through hair follicles or via breaks in the skin. Bacterial serotype O:11 is the most commonly reported isolate for water-associated Pseudomonas folliculitis, but other serotypes that have been reported include O:1, O:3, O:4, O:6, O:7, O:9, O:10, and O:16. Serotype O:11 is possibly more invasive or better adapted to survive in halogenated water. […] Minor trauma from wax depilation or vigorous rubbing with sponges may facilitate the entry of organisms into the skin, and a dose-response relation exists with respect to the degree of water contamination. Hot water, high pH (7.8), and low chlorine level (0.5 mg/L) all predispose to infection.
#41 Pathology Outlines – Folliculitis
https://www.pathologyoutlines.com/topic/skinnontumorfolliculitis.html
Primary inflammation of a hair follicle, either infectious or noninfectious […] Caused by infection, friction and other causes of follicular trauma, excessive perspiration and occlusion […] Infectious cases are either superficial (fungi, bacteria, syphilis, viral) or deep (usually granulomatous and due to either fungi or bacteria) […] Epidermal growth factor receptor (EGFR) inhibitors appear to be relevant in folliculitis by causing abnormal epidermal differentiation that leads to follicular obstruction and subsequent inflammation (Br J Dermatol 2001;144:1169) […] Superficial folliculitis has moderate inflammatory cells in the follicular ostium and upper regions of the follicle […] Infiltrate initially consists of neutrophils, later becomes more mixed with lymphocytes and macrophages.
#42 Bacterial Folliculitis â DermNet
https://dermnetnz.org/topics/bacterial-folliculitis
Folliculitis is inflammation of the hair follicle due to infection, chemical irritation or physical injury. Bacterial folliculitis is usually due to Staphylococcus aureus. Less often, coagulase-negative staphylococci and gram-negative organisms are responsible including anaerobes. Spa pool folliculitis is caused by Pseudomonas. Bacterial folliculitis can lead to cellulitis and lymphangitis; subsequent bacteraemia might result in osteomyelitis, septic arthritis or pneumonia. Bacterial folliculitis is usually diagnosed clinically but can be confirmed by bacterial swabs sent for microscopy, culture and sensitivity. Skin biopsy is rarely necessary. Histology shows dense neutrophilic infiltrate in the subcutaneous tissue and foreign body reaction around a hair shaft. […] The infection with Gram-negative organisms causes pustules in acne sites of the face, neck and upper trunk.
#43 Folliculitis
https://dermnetnz.org/topics/folliculitis
Eosinophilic folliculitis is a specific type of folliculitis that may arise in some immune-suppressed individuals such as those infected by human immunodeficiency virus (HIV) or those who have cancer. […] Folliculitis may be due to drugs, particularly corticosteroids (steroid acne), androgens (male hormones), adrenocorticotrophic hormone (ACTH), lithium, isoniazid (INH), phenytoin and B-complex vitamins. […] Certain uncommon inflammatory skin diseases may cause permanent hair loss and scarring because of deep-seated sterile folliculitis. […] The follicular occlusion syndrome refers to: Hidradenitis suppurativa (acne inversa), Acne conglobata (a severe form of nodulocystic acne), Dissecting cellulitis (perifolliculitis capitis abscedens et suffodiens), Pilonidal sinus. […] Folliculitis affecting the buttocks is quite common in males and females.
#44 Folliculitis â causes and treatment | healthdirect
https://www.healthdirect.gov.au/folliculitis
Folliculitis is an inflammation of the hair follicles in your skin. […] Treatment of folliculitis depends on its cause. […] Non-infective folliculitis can be caused by: shaving and waxing, obesity, heavy sweating. […] Some medicines can also cause folliculitis, such as corticosteroids especially in the form of creams and ointments used on the skin, extended use of antibiotics (which can cause gram negative folliculitis), medicines that suppress the immune system. […] Another type of folliculitis is eosinophilic folliculitis. In some cases, it may start due to immune suppression (your immune system not working properly). […] Infective folliculitis can be caused by: bacteria, viruses, fungi. […] The most common bacteria that cause folliculitis are: staphylococcus aureus (bacterial folliculitis) commonly found on your skin, pseudomonas aeruginosa (hot tub folliculitis) found in hot tubs and spas. […] Some cases of folliculitis can be deeper in the skin and cause boils, which might need treatment with a minor surgical procedure. […] Severe cases of folliculitis may cause scarring and rarely, bald patches.
#45 Abstract
https://www.medicaljournals.se/acta/content/abstract/10.2340/00015555-0759
Eosinophilic pustular folliculitis is an inflammatory skin disease characterized by pruritic follicular papulopustules. […] A PGD2-CRTH2 interaction may be involved in the pathogenesis. […] Moreover, indomethacin may exert its therapeutic effect via reducing CRTH2 expression, as well as by inhibiting PGD2 synthesis.
#46 Malassezia folliculitis in patients with acne vulgaris | CCID
https://www.dovepress.com/the-prevalence-associated-factors-and-clinical-characterization-of-mal-peer-reviewed-fulltext-article-CCID
Malassezia folliculitis (MF) results from an overgrowth of Malassezia yeasts, which are normal skin flora. The abnormal proliferation of yeast can cause inflammation of the hair follicles by two possible mechanisms. The first mechanism is caused by the lipase and phospholipase enzyme activity of Malassezia yeast, damaging skin barrier function and inducing irritation. The second mechanism is the ability of Malassezia yeast that can stimulate keratinocyte production of inflammatory cytokines via Toll-like receptor 2 and activate complement cascades by both the classical and alternative pathways. […] The pustular lesions of MF can be confused with AV. MF can be diagnosed by clinical presentation compatible with laboratory tests such as direct microscopy, histopathology, and fungal culture. A direct microscopic examination for the abnormal proliferation of Malassezia yeasts is positive more often than histology.
#47 Malassezia folliculitis in patients with acne vulgaris | CCID
https://www.dovepress.com/the-prevalence-associated-factors-and-clinical-characterization-of-mal-peer-reviewed-fulltext-article-CCID
Malassezia folliculitis (MF) results from an overgrowth of Malassezia yeasts, which are normal skin flora. The abnormal proliferation of yeast can cause inflammation of the hair follicles by two possible mechanisms. The first mechanism is caused by the lipase and phospholipase enzyme activity of Malassezia yeast, damaging skin barrier function and inducing irritation. The second mechanism is the ability of Malassezia yeast that can stimulate keratinocyte production of inflammatory cytokines via Toll-like receptor 2 and activate complement cascades by both the classical and alternative pathways. […] The pustular lesions of MF can be confused with AV. MF can be diagnosed by clinical presentation compatible with laboratory tests such as direct microscopy, histopathology, and fungal culture. A direct microscopic examination for the abnormal proliferation of Malassezia yeasts is positive more often than histology.
#48 Eosinophilic folliculitis – Therapeutics in Dermatology
https://www.therapeutique-dermatologique.org/spip.php?article1558
Eosinophilic folliculitis is a noninfectious follicular disorder mediated by eosinophils. Its etiology is unknown, although it has been suggested that a T-helper type 2 (Th2) shift may be a possible pathogenic mechanism for the infiltration of eosinophils. […] Histologically, eosinophils predominate in the inflammatory infiltrate involving the perifollicular area and the hair follicle outer rooth sheat which displays spongiotic change. A perivascular and interstitial infiltrate with admixed lymphocytes and eosinophils is often present as well, with negative special stains for microorganisms. Ofujis disease and Eosinophilic pustular folliculitis of infancy are also characterized by the frequent occurrence of epidermal changes with eosinophils exocytosis and spongiosis resulting in small subcorneal or intraepidermal eosinophilic pustules.
#49 Folliculitis Decalvans and Lichen Planopilaris Phenotypic Spectrum With Pityriasis Amiantacea: A Challenging Diagnosis | Actas Dermo-SifiliogrÃ¡ficas
https://actasdermo.org/es-folliculitis-decalvans-lichen-planopilaris-phenotypic-articulo-S0001731023006920
Folliculitis decalvans (FD) and lichen planopilaris (LPP) are primary cicatricial alopecias classified according to the predominant cell-type infiltrate on histopathology. FD is characterized by a neutrophilic infiltrate, while LPP is marked by a lymphocytic inflammation. […] Recently, an overlap of FD and LPP has been described as Folliculitis Decalvans and Lichen Planopilaris Phenotypic Spectrum (FDLPPPS), which combines clinical, trichoscopic and histopathological features of both diseases. […] The pathogenesis is still unclear, but Yip et al. proposed that a microbiome dysbiosis may stimulate an abnormal cell recruitment and collapse hair follicle immune privilege, exposing follicular neoantigens and promoting an exacerbated inflammatory response. […] Histopathological analysis reveals loss of sebaceous glands, multicompound follicular structures, perifollicular fibrosis, atrophy of the follicular epithelium, lymphohistiocytic infiltrate with granulomas, prominent plasma cells, and scarce or absent neutrophils.
#50 Malassezia Folliculitis: Pathogenesis and Diagnostic Challenges
https://pmc.ncbi.nlm.nih.gov/articles/PMC11633069/
Recent research has demonstrated that Cutibacterium acnes, a common skin commensal, can induce epidermal lipid synthesis. […] In MF, it is hypothesized that certain paracrine factors may influence neutrophil activation, leading to their accumulation in the pilosebaceous unit and the formation of follicular pustules. […] The lipids in the hydrophobic matrix of the stratum corneum, as well as sebaceous gland secretions into the hair follicles, likely create an environment that facilitates the aggregation of hydrophobic fungi. […] As with other fungal infections, such as those caused by dermatophytes or dimorphic fungi, the IL-23/IL-17 axis is crucial in mediating the immune response against Malassezia. […] Other receptors, like IL-36R and the aryl hydrocarbon receptor (AhR), may be involved in keratinocyte recognition of Malassezia spp., further influencing the immune response.
#51
https://journals.lww.com/amjdermatopathology/fulltext/2021/12000/eruptive_necrotizing_infundibular_crystalline.2.aspx
The rare phenomenon of NICF may represent an aberrant pathway with disrupted sebaceous follicular histogenesis due to a loss of homeostatic control. […] An important element in NICF is the key roles of regulatory T cells in maintaining homeostatic integrity of sebaceous follicles and also in establishing immune tolerance to skin commensal microbes. […] The introduction of these inhibitors during the critical healing phase of sebaceous folliculitis may play a key role in the aberrant sebaceous metaplasia of infundibular keratinocytes by abrogating the normal differentiation pathway of the infundibulum to directly produce sebum without glandular differentiation.
#52 Role of Staphylococcus aureus in the pathogenesis of folliculitis decalvans | Jedlecka | Forum Dermatologicum
https://journals.viamedica.pl/forum_dermatologicum/article/view/87879
Folliculitis decalvans (FD) is an inflammatory cicatricial alopecia. Its aetiology remains unclear but an imbalance of skin microbiota seems to play a special role in the pathogenesis. […] Previously Staphylococcus aureus (S. aureus) was postulated to play the main role in the pathogenesis of the disease, but recent findings show it is rather opportunistic than a specific pathogen in FD. Staphylococcus aureus colonizing FD does not seem to be more virulent than one isolated from the general population, however, only a partial response to standard anti-staphylococcal antibiotic treatment suggests rather gram-negative aetiology. Antibiotic therapy may prove effective to reduce bacterial load below the threshold that triggers the immune system, but the microbiota found in FD after antibiotic treatment is not entirely restored to normal. Unbalanced microbiota with the reservoir of commensal and opportunistic bacteria in hair follicles may stoke unspecific responses of the immune system, therefore causing chronic inflammation.
#53 Folliculitis
https://dermnetnz.org/topics/folliculitis
Eosinophilic folliculitis is a specific type of folliculitis that may arise in some immune-suppressed individuals such as those infected by human immunodeficiency virus (HIV) or those who have cancer. […] Folliculitis may be due to drugs, particularly corticosteroids (steroid acne), androgens (male hormones), adrenocorticotrophic hormone (ACTH), lithium, isoniazid (INH), phenytoin and B-complex vitamins. […] Certain uncommon inflammatory skin diseases may cause permanent hair loss and scarring because of deep-seated sterile folliculitis. […] The follicular occlusion syndrome refers to: Hidradenitis suppurativa (acne inversa), Acne conglobata (a severe form of nodulocystic acne), Dissecting cellulitis (perifolliculitis capitis abscedens et suffodiens), Pilonidal sinus. […] Folliculitis affecting the buttocks is quite common in males and females.
#54 Hidradenitis Suppurativa: Folliculitis or
https://www.jwatch.org/jd199702010000009/1997/02/01/hidradenitis-suppurativa-folliculitis-or
Hidradenitis is a chronic, inflammatory process that occurs in areas of the body containing apocrine glands. […] Others have maintained that the disease represents a primary folliculitis with secondary occlusion of apocrine and eccrine glands. […] The authors suggest that these findings are similar to those seen in acne vulgaris and provide evidence for a cell-mediated immunologic pathogenesis for this disorder. […] The study does provide convincing evidence that the process is primarily folliculocentric with secondary involvement of apocrine glands, which empty their contents into the follicular outflow tract. […] However, data concerning the pathogenesis as a cell-mediated immunologic response are less convincing.
#55 Hidradenitis Suppurativa: Folliculitis or
https://www.jwatch.org/jd199702010000009/1997/02/01/hidradenitis-suppurativa-folliculitis-or
Hidradenitis is a chronic, inflammatory process that occurs in areas of the body containing apocrine glands. […] Others have maintained that the disease represents a primary folliculitis with secondary occlusion of apocrine and eccrine glands. […] The authors suggest that these findings are similar to those seen in acne vulgaris and provide evidence for a cell-mediated immunologic pathogenesis for this disorder. […] The study does provide convincing evidence that the process is primarily folliculocentric with secondary involvement of apocrine glands, which empty their contents into the follicular outflow tract. […] However, data concerning the pathogenesis as a cell-mediated immunologic response are less convincing.
#56 Infectious folliculitis – UpToDate
https://www.uptodate.com/contents/infectious-folliculitis
Folliculitis refers to inflammation of the superficial or deep portion of the hair follicle. The classic clinical findings of superficial folliculitis are folliculocentric, inflamed papules and/or pustules on hair-bearing skin. Nodules are a feature of deep, follicular inflammation. […] Folliculitis may be infectious or, less frequently, noninfectious. Various bacteria, fungi, viruses, and parasites are causes of infectious folliculitis, with bacteria as the most common cause. […] A correct diagnosis of infectious folliculitis is essential for appropriate management. The patient history and physical examination, particularly the assessment of the distribution of folliculitis, help to narrow the differential diagnosis. Detection of the causative organism confirms the diagnosis and may help direct therapy. […] The etiologies, clinical manifestations, diagnosis, and management of infectious folliculitis will be reviewed here. Noninfectious causes of folliculitis are reviewed separately.
#57 Folliculitis – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK547754/
Folliculitis is a common skin condition that usually involves infection of the hair follicle. While this condition is typically benign, prompt recognition can aid in the improvement of quality of life of patients with this condition. […] Most commonly, infection of the hair follicle is the mechanism behind most folliculitis cases. Even so, folliculitis may also result from fungal or viral infections, but this does not mean that all folliculitis cases are infectious. Sometimes, folliculitis may be the result of inflammation secondary to ingrown hairs as well as caused by certain drugs such as lithium and cyclosporine.