Materiały źródłowe

• #1 Onychomycosis: Current Trends in Diagnosis and Treatment | AAFP

  https://www.aafp.org/pubs/afp/issues/2013/1201/p762.html

  Onychomycosis is a fungal infection of the nails that causes discoloration, thickening, and separation from the nail bed. Accurate diagnosis involves physical and microscopic examination and culture. Histologic evaluation using periodic acidSchiff staining increases sensitivity for detecting infection. […] Accurate diagnosis is crucial for successful treatment and requires identification of physical changes and positive laboratory analysis. Only 50% of nail problems are caused by onychomycosis, and clinical diagnosis by physical examination alone can be inaccurate. […] Laboratory analysis involves evaluation of nail clippings and subungual debris from the involved portion of the nail. Samples should be collected after cleansing the area with 70% isopropyl alcohol to prevent contamination.

• #1 Nail fungus – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/nail-fungus/symptoms-causes/syc-20353294

  Nail fungus is a common infection of the nail. It begins as a white or yellow-brown spot under the tip of your fingernail or toenail. […] You may want to see a health care provider if self-care steps haven’t helped and the nail becomes increasingly discolored, thickened or misshapen. […] Nail fungus is caused by various fungal organisms (fungi). The most common is a type called dermatophyte. […] Fungal infection of the foot (athlete’s foot) can spread to the nail, and a fungal infection of the nail can spread to the foot. […] A severe case of nail fungus can be painful and may cause permanent damage to your nails. […] The following habits can help prevent nail fungus or reinfections and athlete’s foot, which can lead to nail fungus: Keep your nails clean and dry.

• #1 Diagnosing and Treating Nail Fungus – MD Atlanta

  https://mdatl.com/2015/01/diagnosing-treating-nail-fungus/

  If the fungal culture returns negative, be sure the patient has not used topical antifungal preparation prior to the culture. Taking a second culture for fungus of the nails is helpful. If the second culture is negative, the problem may not be nail fungus. […] The differential diagnosis of nail fungus includes psoriasis, lichen planus, squamous cell carcinoma, verruca, and other eczematous dermatosis. […] If the nail culture is negative on two samples, consider a podiatry or dermatology consultation. If the nail is painful, bleeding or shows erythema, it may be important to send the patient for a nail bed biopsy. […] Treatment of nail fungus is challenging. The toenail grows slowly, only 1mm per month, fully regrowing in 12 to 18 months. The fingernail may regrow in six months. […] Oral medications are not always effective, have systemic risk and may interact with other medications.

• #1 Diagnosis of Onychomycosis: From Conventional Techniques and Dermoscopy to Artificial Intelligence

  https://pmc.ncbi.nlm.nih.gov/articles/PMC8081953/

  Onychomycosis is a common fungal nail infection. Accurate diagnosis is critical as onychomycosis is transmissible between humans and impacts patients’ quality of life. Combining clinical examination with mycological testing ensures accurate diagnosis. Conventional diagnostic techniques, including potassium hydroxide testing, fungal culture and histopathology of nail clippings, detect fungal species within nails. […] To diagnose onychomycosis, clinical suspicion needs to be confirmed with mycologic testing. This review highlights key characteristics of conventional diagnostic tools, including potassium hydroxide (KOH) testing, fungal culture and histopathology of nail clippings, and newly developed techniques, including dermoscopy, reflectance confocal microscopy, molecular assays and artificial intelligence.

• #1 Onychomycosis: Pathogenesis, Diagnosis, and Management

  https://pmc.ncbi.nlm.nih.gov/articles/PMC88888/

  Both direct microscopy and in vitro laboratory culture of sampled material are necessary to definitively identify the etiologic agent. […] The specimen should be divided into two portions for direct microscopy and culture. […] Direct microscopy is often time-consuming, because nail debris is thick and coarse and hyphae are usually only sparsely present. […] The last three decades have seen unequivocal documentation of the role of nondermatophytes as causal agents in onychomycosis. […] The most common yeast that is involved is C. albicans. […] The specimen can be mounted in a solution of 20 to 25% KOH or NaOH mixed with 5% glycerol, heated to emulsify lipids, and examined under 40 magnification. […] Culture is the only method by which the causative microorganism can be identified.

• #1 Onychomycosis Workup: Laboratory Studies, Other Tests, Procedures

  https://emedicine.medscape.com/article/1105828-workup

  The clinical features of onychomycosis (OM) may mimic those of numerous other nail disorders. Therefore, laboratory diagnosis of OM must be confirmed before any treatment regimen is begun. A negative mycologic result does not rule out OM, because direct microscopy may be negative in as many as 10% of cases and culture in as many as 30%. […] Direct microscopy cannot identify the specific pathogen involved in OM. A fungal culture must be obtained to identify the species of organism. Nondermatophyte molds may be resistant to the conventional therapy used for the more common dermatophytes. Therefore, two types of growth medium should be used: one with cycloheximide (dermatophyte test medium [DTM], Mycosel, or Mycobiotic) to select for dermatophytes and one without cycloheximide (Sabouraud glucose agar, Littman oxgall medium, or inhibitory mold agar) to isolate yeasts and nondermatophyte molds.

• #1 Diagnosis of Onychomycosis: From Conventional Techniques and Dermoscopy to Artificial Intelligence

  https://pmc.ncbi.nlm.nih.gov/articles/PMC8081953/

  KOH testing has 61% sensitivity and 95% specificity. It is cost-effective and can determine the presence of fungal organisms within an hour. However, it cannot specify the exact type of pathogenic organism. […] Fungal culture can identify the specific pathogen subtype. […] Histopathology of nail clippings is highly sensitive (84%) and specific (89%). […] Nail dermoscopy (onychoscopy) is a non-invasive bedside tool that allows clinicians to visualize microscopic features of abnormal nails. […] Reflectance confocal microscopy (RCM) is a real-time imaging tool that allows clinicians to observe features of abnormal nails at near-histologic resolution by the bedside. […] Molecular assays including polymerase chain reactions (PCR), flow cytometry and mass spectrometry are advanced diagnostic tools that involve analysis of the fungal DNA causing onychomycosis.

• #1 Onychomycosis Workup: Laboratory Studies, Other Tests, Procedures

  https://emedicine.medscape.com/article/1105828-workup

  Histologic examination of the nail is a highly useful alternative to culture or KOH testing. Nail clippings may be sent to the laboratory for diagnosis in a formalin-filled container, or, as a last resort, an incisional nail biopsy (by punch or scalpel) may be performed to help confirm the diagnosis.

• #1 Clinical Diagnosis and Laboratory Testing of Abnormal Appearing Toenails: A Retrospective Assessment of Confirmatory Testing for Onychomycosis in the United States, 2022–2023

  https://www.mdpi.com/2309-608X/10/2/149

  Onychomycosis is an under-recognized healthcare burden. Despite the risk of misdiagnosis, confirmatory laboratory testing is under-utilized. Histopathologic examination with polymerase chain reaction (PCR) is currently the most effective diagnostic method; it offers direct detection and identification of a fungal invasion. […] Performing a histopathologic examination with PCR was more likely to provide pathogen identification results than using fungal culture. […] Our results support the use of confirmatory laboratory testing when there is a clinical diagnosis of onychomycosis. […] Traditional methods of testing for onychomycosis include KOH direct microscopy, fungal culture and histopathologic examination, while emerging diagnostic modalities utilizing techniques such as polymerase chain reaction (PCR) offer promising potential in improving diagnostic sensitivity and turnaround time.

• #1 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicy/external-policies/onychomycosis-testing/

  To screen for, diagnose, or confirm onychomycosis, attenuated total-reflectance fourier transform infrared (ATR-FTIR) spectroscopy is considered NOT MEDICALLY NECESSARY. […] Testing for the presence of fungal-derived sterols (e.g., ergosterol) is considered NOT MEDICALLY NECESSARY. […] Proprietary Testing An onychomycosis diagnosis should be given based on both clinical results and mycological lab results. Several types of tests have been developed to diagnose onychomycosis. The current diagnostic gold standard includes direct microscopy with potassium hydroxide (KOH) and fungal culture, as these methods can identify the pathogenic species and fungal viability; additional tests include polymerase chain reaction (PCR) testing, fluorescent staining and periodic acid-Schiff (PAS) staining. It has been reported that KOH testing is only 60% sensitive and cannot identify the species, but it can differentiate between dermatophytes and saprophytes based on a positive result; Currently, the most sensitive test (95%) is a pathologist interpreted nail clip biopsy that has been stained with periodic acid-Schiff (PAS) plus Grocott methenamine silver. Mycologic culture may be used for suspected onychomycosis cases with negative KOH results if spores, hyphae, or other fungal structures were seen via microscopy; histologic evaluation of a nail clipping using PAS stain may assist in an onychomycosis diagnosis with more sensitive results than those given by mycologic culture. An Aspergillus species causative agent may be suspected with a negative culture result but a positive KOH test. Fungal cultures must be interpreted by a mycologist and, while they are specific, they are only about 60% sensitive and take several weeks to grow. When utilized together, fungal culture and PCR can determine the source of the infection; the addition of PCR can improve species detection by 20% and will assist in differentiating between onychomycosis and nail dystrophy. PCR, when used with fungal culture, allows for a much faster, highly sensitive, and very specific diagnosis. Multiplex qPCR assays have shown to be reliable for onychomycosis diagnostics with a shorter response time than traditional culture methods.

• #1 Onychomycosis: Pathogenesis, Diagnosis, and Management

  https://pmc.ncbi.nlm.nih.gov/articles/PMC88888/

  Although not life-threatening, onychomycosis (a fungal infection of the nail, usually caused by a dermatophyte) constitutes an important public health problem because of its high prevalence (about 10% of the U.S. population) and associated morbidity. […] Accurate diagnosis requires direct microscopy and fungal culture. […] The clinical presentation of dystrophic nails should alert the clinician to the possibility of onychomycosis; however, because fungi cause only about half of all nail dystrophies, the use of appropriate diagnostic techniques including direct microscopy and fungal culture is important to ensure correct diagnosis and treatment. […] The first step of the sample collection process is thorough cleansing of the nail area with alcohol to remove contaminants such as bacteria.

• #1 Culture, Fungus, Skin, Hair or Nails | Test Detail | Quest Diagnostics

  https://testdirectory.questdiagnostics.com/test/test-detail/39515/culture-fungus-skin-hair-or-nails?p=r&cc=MASTER

  Culture, Fungus, Skin, Hair or Nails – Fungi cause many types of infections, some of which may become serious, especially in immunocompromised and hospitalized patients. The appropriate collection, transport and processing of specimens allows the recovery of fungal organisms and the association of a specific fungus with a disease process. […] Fungal Culture, Isolation and Identification […] Basal portions of infected hairs, scrapings from the active, peripheral edge of lesions and scrapings from recently invaded nail tissue […] Remove hairs with forceps, scrape skin or scalp scales, clip nails and include keratin scrapings. Cleanse skin with alcohol before scraping. Cleanse feet and hands before collecting nails. Refrigeration is not recommended because it can inhibit dermatophytes. […] Sterile leak-proof container Dry swab in sterile container Swab in bacterial transport medium […] Room temperature.

• #1 Fungal Nail Infections — DermNet

  https://dermnetnz.org/topics/fungal-nail-infections

  How is onychomycosis diagnosed? […] Physical examination of all nails, and a combination of tools, such as those listed below, may be used to improve speed and accuracy of diagnosis. […] Dermoscopy may be able to differentiate between onychomycosis, traumatic onycholysis, and melanonychia. […] Clippings should be taken from the crumbling free edge of the affected nail. […] Microscopic examination reviewed under light microscopy using potassium hydroxide (to dissolve keratinocyte material) is a quick test to assess for the presence of fungal hyphae, although it lacks sensitivity and specificity. […] Fungal cultures can identify the causative organism and is the standard diagnostic test, however, results can take weeks and a large specimen collection may be required. […] PCR testing quickly identifies the offending organism and is highly sensitive and specific. […] A nail biopsy may also reveal characteristic histopathological features of onychomycosis.

• #1 Culture, Fungus, Skin, Hair, Nail with Direct Fluorescent/KOH | Test Detail | Quest Diagnostics

  https://testdirectory.questdiagnostics.com/test/test-detail/4605/culture-fungus-skin-hair-nail-with-direct-fluorescentkoh?p=r&cc=MASTER

  Culture, Fungus, Skin, Hair, Nail with Direct Fluorescent/KOH – Fungi cause many types of infections, some of which may become serious, especially in immunocompromised and hospitalized patients. The appropriate collection, transport and processing of specimens allows the recovery of fungal organisms and the association of a specific fungus with a disease process. […] Preferred Specimen(s): Basal portions of infected hairs, scrapings from the active, peripheral edge of lesions and scrapings from recently invaded nail tissue. […] Collection Instructions: Remove hairs with forceps, scrape skin or scalp scales, clip nails and include keratin scrapings. Cleanse skin with alcohol before scraping. Cleanse feet and hands before collecting nails. Refrigeration is not recommended because it can inhibit dermatophytes. […] Transport Temperature: Room temperature. […] Specimen Stability: Transport swabs Room temperature: 72 hours Refrigerated: See Instructions Frozen: Unacceptable Hair, skin and nail specimens Room temperature: 14 days Refrigerated: See instructions Frozen: Unacceptable.

• #1 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicy/external-policies/onychomycosis-testing/

  Policy Application of coverage criteria is dependent upon an individuals benefit coverage at the time of the request. […] For individuals with onychomycosis, direct microscopic examination with potassium hydroxide, fungal culture of desquamated subungual material, or fungal stain of a nail clipping(s) is considered MEDICALLY NECESSARY. […] For individuals with onychomycosis and for whom trial and failure of oral anti-fungals or documented reasons why oral treatment is contraindicated (i.e., liver disease) has failed to resolve infection, nucleic acid amplification testing (NAAT) is considered MEDICALLY NECESSARY. […] To screen for, diagnose, or confirm onychomycosis, NAAT is considered NOT MEDICALLY NECESSARY. […] The following does not meet coverage criteria due to a lack of available published scientific literature confirming that the test(s) is/are required and beneficial for the diagnosis and treatment of an individuals illness.

• #1 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicy/external-policies/onychomycosis-testing/

  The CDC remarks that an onychomycosis infection may be diagnosed through visual inspection, questioning the patient on their symptoms, or a fungal culture. The CDC states healthcare providers may take a small skin scraping or nail sample for testing. […] The CDC also notes that the term onychomycosis is the technical term for a fungal nail infection. It can be caused by ringworm or by infection with other types of fungi such as yeasts. Onychomycosis can affect the fingernails or toenails, but onychomycosis of the toenails is more common. […] Within the AAPs Red Book, recommendations include the following concerning diagnostic testing for onychomycosis: Fungal infection of the nail (tinea unguium or onychomycosis) can be verified by direct microscopic examination with potassium hydroxide, fungal culture of desquamated subungual material, or fungal stain of a nail clippings fixed in formalin.

• #1

  https://bpac.org.nz/BT/2011/March/fungal-infections.aspx

  Fungal infections of the skin, nails and hair are caused by dermatophytes. […] Diagnosis of a fungal infection is often made by clinical appearance alone, but sometimes laboratory examination of skin scrapings, hair or nail cuttings can help when the diagnosis is uncertain. […] Specimens should be sent to confirm disease when the infection is chronic, severe or when considering systemic therapy. Laboratory fungal testing is also justifiable in the following circumstances: To confirm fungal infection before starting on oral treatment, e.g. if the patient has been treating the lesion with topical steroids or a fungal infection involving the hair, palms of the hands or soles of the feet. […] Nail cuttings should also be collected. […] A negative culture result may arise due to: Feature of methodology, Incorrect initial clinical diagnosis, Sampling errors associated with poor collection technique, Sampling errors associated with inadequate specimen, The presence of non-viable hyphae elements in the distal region of a nail, An uneven colonisation of a nail with the fungus, Overgrowth by contaminant saprophytic fungi, Anti-fungal treatment used prior to collection of the specimen, A delay in the specimen reaching the laboratory, Incorrect laboratory procedures, Slow growth of the organism.

• #1 Onychomycosis – Dermatologic Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/dermatologic-disorders/nail-disorders/onychomycosis

  Onychomycosis is fungal infection of the nail plate, nail bed, or both. Diagnosis is by appearance, wet mount, culture, polymerase chain reaction, or a combination. […] Onychomycosis is suspected by appearance in patients who also have tinea pedis; predictive clinical features include involvement of the 3rd or 5th toenail, involvement of the 1st and 5th toenails on the same foot, and unilateral nail deformity. […] Differentiation from psoriasis or lichen planus is important because the therapies differ, so diagnosis is typically confirmed by microscopic examination and, unless microscopic findings are conclusive, culture of scrapings or PCR of clippings. […] Although more expensive, PCR has become a more common technique to confirm the diagnosis of onychomycosis, especially if cultures are negative or a definitive diagnosis is required. […] Obtaining an adequate sample of nail for culture can be difficult because the distal subungual debris, which is easy to sample, often does not contain living fungus.

• #1 Fungal nail infection: diagnosis and management | The BMJ

  https://www.bmj.com/content/348/bmj.g1800

  Friable nail plate and nail spikes (yellow hyperkeratotic bands) suggest onychomycosis […] Histopathology of nail clippings can be done easily and quickly and is an economical way to establish a pathogenic role of fungi; specimens can be sent without fixatives or transport medium and results are available in 3-5 days […] Treatment should not be started before confirmation of infection by mycology […] False negative rates for culture are 30%; therefore a negative test result cannot exclude infection and should be repeated if clinical suspicion is high […] Consider non-dermatophyte moulds if onychomycosis is unresponsive to antifungals, and if microscopy provides a positive result but cultures give negative results.

• #1 Fungal Nail Infection: Overview, Causes & Treatments

  https://www.healthline.com/health/fungal-nail-infection

  Fungal nail infections are common and are caused by fungi that live in the environment. […] Onychomycosis, also called tinea unguium, is a fungal infection that affects either the fingernails or toenails. […] Because other infections can affect the nail and mimic symptoms of a fungal nail infection, the only way to confirm a diagnosis is to see a doctor. Theyll take a scraping of the nail and look under a microscope for signs of fungus. […] In some cases, your doctor may send the sample to a lab for analysis and identification. […] Over-the-counter products arent usually recommended to treat nail infections since they dont provide reliable results. Instead, your doctor may prescribe an oral antifungal medication, such as: terbinafine (Lamisil), itraconazole (Sporanox), fluconazole (Diflucan), griseofulvin (Gris-PEG). […] Your doctor may prescribe other antifungal treatments, such as antifungal nail lacquer or topical solutions. […] Treatment isnt guaranteed to completely rid your body of the fungal infection. […] Its especially important to see your doctor if you have diabetes and a fungal nail infection.

• #1 Toenail Fungus (Onychomycosis/Tinea Unguium): Symptoms & Causes

  https://my.clevelandclinic.org/health/diseases/11303-toenail-fungus

  The most effective toenail fungus treatment for you will largely depend on your symptoms and situation. Your healthcare provider will consider several factors before recommending a treatment plan. Theyll customize a treatment plan for you. […] Overall, oral antifungal medications may offer the most treatment potential. Pairing oral drugs with topical antifungal medication may make treatment more effective.

• #1 Nail fungus: Diagnosis and treatment

  https://www.aad.org/public/diseases/a-z/nail-fungus-treatment

  To find out if a patient has nail fungus, a dermatologist examines your nails and nearby skin. Its important to check the skin because the fungus can spread. You may already have a skin infection caused by fungus like athletes foot. […] Before giving you the diagnosis, your dermatologist may also take some samples. Collecting a bit of debris from beneath a nail, trimming off part your nail, or scraping off a bit of skin can be very helpful. In a lab, these samples can be examined under a microscope to find out whats causing the problem. […] The FDA has approved the following systemic (works throughout the body) medicines to treat nail fungus: Fluconazole, Griseofulvin, Itraconazole, Terbinafine. […] With treatment, many people can get rid of nail fungus. Even when the fungus clears, your nail(s) may look unhealthy until the infected nail grows out. A fingernail grows out in 4 to 6 months and a toenail in 12 to 18 months. […] Nail fungus can be stubborn. If you had a severe infection, its possible to clear the infection. A healthy looking nail, however, may be unrealistic, but you can expect the nail to look better and feel more comfortable.

• #1 Onychomycosis: Pathogenesis, Diagnosis, and Management

  https://pmc.ncbi.nlm.nih.gov/articles/PMC88888/

  The recommendations for intermittent therapy with fluconazole are unknown. […] In all cases, patients should be educated so that they can recognize and report signs of drug-related adverse reactions, including jaundice, upper abdominal tenderness, malaise, dark urine, pale stools, fatigue, nausea, and vomiting.

• #2 Onychomycosis: Pathogenesis, Diagnosis, and Management

  https://pmc.ncbi.nlm.nih.gov/articles/PMC88888/

  Although not life-threatening, onychomycosis (a fungal infection of the nail, usually caused by a dermatophyte) constitutes an important public health problem because of its high prevalence (about 10% of the U.S. population) and associated morbidity. […] Accurate diagnosis requires direct microscopy and fungal culture. […] The clinical presentation of dystrophic nails should alert the clinician to the possibility of onychomycosis; however, because fungi cause only about half of all nail dystrophies, the use of appropriate diagnostic techniques including direct microscopy and fungal culture is important to ensure correct diagnosis and treatment. […] The first step of the sample collection process is thorough cleansing of the nail area with alcohol to remove contaminants such as bacteria.

• #2 Onychomycosis: Rapid Evidence Review | AAFP

  https://www.aafp.org/pubs/afp/issues/2021/1000/p359.html

  Onychomycosis should be suspected in patients with discolored nails, nail plate thickening, nail separation, and foul-smelling nails. […] Accurate diagnosis is important before initiating treatment because therapy is lengthy and can cause adverse effects. […] A potassium hydroxide preparation with confirmatory fungal culture, periodic acidSchiff stain, or polymerase chain reaction is the preferred diagnostic approach if confirmative testing is cost prohibitive or not available. […] Laboratory confirmation of nail infection is important for accurate diagnosis. […] A potassium hydroxide (KOH) preparation with direct microscopy is the preferred diagnostic method because it is highly specific, has rapid results, and is cost-effective. […] Diagnosis by KOH preparation alone is sufficient for treatment initiation. However, if KOH results are negative and there is high clinical suspicion for onychomycosis, other testing may be performed to confirm the diagnosis. […] Diagnostic testing is generally recommended before initiating treatment, but empiric treatment with terbinafine can be considered if testing is cost prohibitive.

• #2 Nail fungal infection: Causes, treatment, and symptoms

  https://www.medicalnewstoday.com/articles/151952

  Nail fungal infections include onychomycosis and tinea unguium. […] Diagnosis is carried out by examination of the debris under the nail. […] In order to diagnose nail fungus infections, a doctor will usually examine debris that is scraped from underneath the nail. The nail scrapings will be used in tests, such as a potassium hydroxide (KOH) smear, or a fungal culture. The KOH test can be quickly performed, while the fungal culture can take weeks. […] Physicians must be careful when diagnosing fungal infections of the nail because several other conditions can result in similar symptoms.

• #2 Diagnosis of Onychomycosis: From Conventional Techniques and Dermoscopy to Artificial Intelligence

  https://pmc.ncbi.nlm.nih.gov/articles/PMC8081953/

  KOH testing has 61% sensitivity and 95% specificity. It is cost-effective and can determine the presence of fungal organisms within an hour. However, it cannot specify the exact type of pathogenic organism. […] Fungal culture can identify the specific pathogen subtype. […] Histopathology of nail clippings is highly sensitive (84%) and specific (89%). […] Nail dermoscopy (onychoscopy) is a non-invasive bedside tool that allows clinicians to visualize microscopic features of abnormal nails. […] Reflectance confocal microscopy (RCM) is a real-time imaging tool that allows clinicians to observe features of abnormal nails at near-histologic resolution by the bedside. […] Molecular assays including polymerase chain reactions (PCR), flow cytometry and mass spectrometry are advanced diagnostic tools that involve analysis of the fungal DNA causing onychomycosis.

• #2 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicy/external-policies/onychomycosis-testing/

  To screen for, diagnose, or confirm onychomycosis, attenuated total-reflectance fourier transform infrared (ATR-FTIR) spectroscopy is considered NOT MEDICALLY NECESSARY. […] Testing for the presence of fungal-derived sterols (e.g., ergosterol) is considered NOT MEDICALLY NECESSARY. […] Proprietary Testing An onychomycosis diagnosis should be given based on both clinical results and mycological lab results. Several types of tests have been developed to diagnose onychomycosis. The current diagnostic gold standard includes direct microscopy with potassium hydroxide (KOH) and fungal culture, as these methods can identify the pathogenic species and fungal viability; additional tests include polymerase chain reaction (PCR) testing, fluorescent staining and periodic acid-Schiff (PAS) staining. It has been reported that KOH testing is only 60% sensitive and cannot identify the species, but it can differentiate between dermatophytes and saprophytes based on a positive result; Currently, the most sensitive test (95%) is a pathologist interpreted nail clip biopsy that has been stained with periodic acid-Schiff (PAS) plus Grocott methenamine silver. Mycologic culture may be used for suspected onychomycosis cases with negative KOH results if spores, hyphae, or other fungal structures were seen via microscopy; histologic evaluation of a nail clipping using PAS stain may assist in an onychomycosis diagnosis with more sensitive results than those given by mycologic culture. An Aspergillus species causative agent may be suspected with a negative culture result but a positive KOH test. Fungal cultures must be interpreted by a mycologist and, while they are specific, they are only about 60% sensitive and take several weeks to grow. When utilized together, fungal culture and PCR can determine the source of the infection; the addition of PCR can improve species detection by 20% and will assist in differentiating between onychomycosis and nail dystrophy. PCR, when used with fungal culture, allows for a much faster, highly sensitive, and very specific diagnosis. Multiplex qPCR assays have shown to be reliable for onychomycosis diagnostics with a shorter response time than traditional culture methods.

• #2 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicyhb/external-policies/onychomycosis-testing/

  To screen for, diagnose, or confirm onychomycosis, attenuated total-reflectance fourier transform infrared (ATR-FTIR) spectroscopy is considered NOT MEDICALLY NECESSARY. […] Testing for the presence of fungal-derived sterols (e.g., ergosterol) is considered NOT MEDICALLY NECESSARY. […] An onychomycosis diagnosis should be given based on both clinical results and mycological lab results. […] Several types of tests have been developed to diagnose onychomycosis. The current diagnostic gold standard includes direct microscopy with potassium hydroxide (KOH) and fungal culture, as these methods can identify the pathogenic species and fungal viability; additional tests include polymerase chain reaction (PCR) testing, fluorescent staining and periodic acid-Schiff (PAS) staining. […] It has been reported that KOH testing is only 60% sensitive and cannot identify the species, but it can differentiate between dermatophytes and saprophytes based on a positive result; Currently, the most sensitive test (95%) is a pathologist interpreted nail clip biopsy that has been stained with periodic acid-Schiff (PAS) plus Grocott methenamine silver.

• #2 Onychomycosis Workup: Laboratory Studies, Other Tests, Procedures

  https://emedicine.medscape.com/article/1105828-workup

  Histologic examination of the nail is a highly useful alternative to culture or KOH testing. Nail clippings may be sent to the laboratory for diagnosis in a formalin-filled container, or, as a last resort, an incisional nail biopsy (by punch or scalpel) may be performed to help confirm the diagnosis.

• #2 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicy/external-policies/onychomycosis-testing/

  Further, the BAD also stated that Traditionally, laboratory detection and identification of dermatophytes consists of culture and microscopy, which yields results within approximately two to six weeks. Calcofluor white is exceedingly useful for direct microscopic examination of nail specimens, as the fungal elements are seen much more easily than with potassium hydroxide, thereby increasing sensitivity. […] More recent molecular genetic tools were also highlighted as a newer diagnostic technique for the detection of dermatophytes. Regarding PCR testing, the BAD has stated that Realtime polymerase chain reaction (PCR) assays have been developed, which simultaneously detect and identify the most prevalent dermatophytes directly in nail, skin and hair samples and have a turnaround time of two days. It appears that realtime PCR significantly increased the detection rate of dermatophytes compared with culture. However, PCR may detect nonpathogenic or dead fungus, which could limit its use in identifying the true pathogen. Restriction fragment length polymorphism analysis, which identifies fungal ribosomal DNA, is very helpful for defining whether the disease is caused by repeat infection or another fungal strain when there is a lack of response to treatment. However, this technique has not been implemented into routine clinical practice.

• #2 Clinical Diagnosis and Laboratory Testing of Abnormal Appearing Toenails: A Retrospective Assessment of Confirmatory Testing for Onychomycosis in the United States, 2022–2023

  https://www.mdpi.com/2309-608X/10/2/149

  An accurate diagnosis of onychomycosis requires confirmatory laboratory testing, in addition to a thorough physical examination. Out of the available techniques, the most effective testing method is a combined histopathologic examination, where PCR testing as the first test indicates evidence of a fungal invasion in the nail plate and the second test provides pathogen identification. […] This finding further corroborates the general consensus that only about half of the clinically suspected cases of onychomycosis are proven positive by laboratory testing and reinforces our viewpoint that clinical diagnosis of onychomycosis is not sufficient as a solitary diagnostic approach; laboratory testing must be performed. […] Current gaps in onychomycosis management practices expose patients to higher risks of misdiagnosis and mistreatment. Healthcare providers treating patients who are clinically suspected of having onychomycosis should consider submitting nail samples for confirmatory laboratory testing prior to initiating treatment; doing so would not only exclude the possibility of other common nail disorders and mitigate risks associated with systemic agents, but also increase the likelihood of a positive clinical response and higher patient satisfaction.

• #2 Fungal Nail Infections — DermNet

  https://dermnetnz.org/topics/fungal-nail-infections

  How is onychomycosis diagnosed? […] Physical examination of all nails, and a combination of tools, such as those listed below, may be used to improve speed and accuracy of diagnosis. […] Dermoscopy may be able to differentiate between onychomycosis, traumatic onycholysis, and melanonychia. […] Clippings should be taken from the crumbling free edge of the affected nail. […] Microscopic examination reviewed under light microscopy using potassium hydroxide (to dissolve keratinocyte material) is a quick test to assess for the presence of fungal hyphae, although it lacks sensitivity and specificity. […] Fungal cultures can identify the causative organism and is the standard diagnostic test, however, results can take weeks and a large specimen collection may be required. […] PCR testing quickly identifies the offending organism and is highly sensitive and specific. […] A nail biopsy may also reveal characteristic histopathological features of onychomycosis.

• #2 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicy/external-policies/onychomycosis-testing/

  Finally, the BAD also stated that histopathological analysis using periodic acid-Schiff staining is more sensitive than direct microscopy or culture. However, this technique is not currently available in the majority of dermatology clinics or mycology laboratories. Other diagnostic techniques under investigation include flow cytometry and confocal and scanning electron microscopy.

• #2 Culture, Fungus, Skin, Hair, Nail with Direct Fluorescent/KOH | Test Detail | Quest Diagnostics

  https://testdirectory.questdiagnostics.com/test/test-detail/4605/culture-fungus-skin-hair-nail-with-direct-fluorescentkoh?p=r&cc=MASTER

  Culture, Fungus, Skin, Hair, Nail with Direct Fluorescent/KOH – Fungi cause many types of infections, some of which may become serious, especially in immunocompromised and hospitalized patients. The appropriate collection, transport and processing of specimens allows the recovery of fungal organisms and the association of a specific fungus with a disease process. […] Preferred Specimen(s): Basal portions of infected hairs, scrapings from the active, peripheral edge of lesions and scrapings from recently invaded nail tissue. […] Collection Instructions: Remove hairs with forceps, scrape skin or scalp scales, clip nails and include keratin scrapings. Cleanse skin with alcohol before scraping. Cleanse feet and hands before collecting nails. Refrigeration is not recommended because it can inhibit dermatophytes. […] Transport Temperature: Room temperature. […] Specimen Stability: Transport swabs Room temperature: 72 hours Refrigerated: See Instructions Frozen: Unacceptable Hair, skin and nail specimens Room temperature: 14 days Refrigerated: See instructions Frozen: Unacceptable.

• #2

  https://bpac.org.nz/BT/2011/March/fungal-infections.aspx

  Fungal infections of the skin, nails and hair are caused by dermatophytes. […] Diagnosis of a fungal infection is often made by clinical appearance alone, but sometimes laboratory examination of skin scrapings, hair or nail cuttings can help when the diagnosis is uncertain. […] Specimens should be sent to confirm disease when the infection is chronic, severe or when considering systemic therapy. Laboratory fungal testing is also justifiable in the following circumstances: To confirm fungal infection before starting on oral treatment, e.g. if the patient has been treating the lesion with topical steroids or a fungal infection involving the hair, palms of the hands or soles of the feet. […] Nail cuttings should also be collected. […] A negative culture result may arise due to: Feature of methodology, Incorrect initial clinical diagnosis, Sampling errors associated with poor collection technique, Sampling errors associated with inadequate specimen, The presence of non-viable hyphae elements in the distal region of a nail, An uneven colonisation of a nail with the fungus, Overgrowth by contaminant saprophytic fungi, Anti-fungal treatment used prior to collection of the specimen, A delay in the specimen reaching the laboratory, Incorrect laboratory procedures, Slow growth of the organism.

• #2 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicy/external-policies/onychomycosis-testing/

  The CDC remarks that an onychomycosis infection may be diagnosed through visual inspection, questioning the patient on their symptoms, or a fungal culture. The CDC states healthcare providers may take a small skin scraping or nail sample for testing. […] The CDC also notes that the term onychomycosis is the technical term for a fungal nail infection. It can be caused by ringworm or by infection with other types of fungi such as yeasts. Onychomycosis can affect the fingernails or toenails, but onychomycosis of the toenails is more common. […] Within the AAPs Red Book, recommendations include the following concerning diagnostic testing for onychomycosis: Fungal infection of the nail (tinea unguium or onychomycosis) can be verified by direct microscopic examination with potassium hydroxide, fungal culture of desquamated subungual material, or fungal stain of a nail clippings fixed in formalin.

• #2 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicyhb/external-policies/onychomycosis-testing/

  The CDC remarks that an onychomycosis infection may be diagnosed through visual inspection, questioning the patient on their symptoms, or a fungal culture. The CDC states to confirm the diagnosis, the healthcare provider might collect a nail clipping to look at under a microscope or to send to a laboratory for testing. […] Within the AAPs Red Book, recommendations include the following concerning diagnostic testing for onychomycosis: Fungal infection of the nail (tinea unguium or onychomycosis) can be verified by direct microscopic examination with potassium hydroxide, fungal culture of desquamated subungual material, or fungal stain of a nail clippings fixed in formalin. […] The BAD have published guidelines for the management of onychomycosis stating that The clinical characteristics of dystrophic nails must alert the clinician to the possibility of onychomycosis. Laboratory confirmation of a clinical diagnosis of tinea unguium should be obtained before starting treatment. […] More recent molecular genetic tools were also highlighted as a newer diagnostic technique for the detection of dermatophytes.

• #2 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicy/external-policies/onychomycosis-testing/

  The AAP also notes that confirmatory diagnostic tests are similar to those for tinea corporis. According to the AAP Red Book, fungal culture to diagnose tinea corporis can be used, but that polymerase chain reaction and periodic acid-Schiff stain evaluation of specimens are available but are expensive and generally are not necessary. […] The BAD have published guidelines for the management of onychomycosis stating that The clinical characteristics of dystrophic nails must alert the clinician to the possibility of onychomycosis. Laboratory confirmation of a clinical diagnosis of tinea unguium should be obtained before starting treatment. This is important for several reasons: to eliminate nonfungal dermatological conditions from the diagnosis; to detect mixed infections; and to diagnose patients with less responsive forms of onychomycosis, such as toenail infections due to T. rubrum. Good nail specimens are difficult to obtain but are crucial for maximizing laboratory diagnosis. Material should be taken from any discoloured, dystrophic, or brittle parts of the nail.

• #2 Nail Fungus Pictures, Types, Causes, Symptoms, Best Treatment

  https://www.medicinenet.com/fungal_nails/article.htm

  How do healthcare professionals diagnose fungal nails? […] Physical exam alone is an unreliable method of diagnosing fungal nails. Many conditions can make nails look damaged, so even doctors have a difficult time. Studies have found that only about 50% of cases of abnormal nail appearance were caused by fungus. Therefore, laboratory testing is almost always indicated. Some insurance companies may even ask for a laboratory test confirmation of the diagnosis for antifungal medicine to be covered. […] A nail sample is obtained either by clipping the toenail or by drilling a hole in the nail. That piece of nail is sent to a lab where it can be stained, cultured, or tested by PCR (to identify the genetic material of the organisms) to identify the presence of fungus. […] Staining and culturing can take up to six weeks to get a result, but PCR to identify the fungal genetic material, if available, can be done in about one day. However, this test is not widely used due to its high cost. […] If a negative biopsy result is accompanied by high clinical suspicion, such as nails that are ragged, discolored, thickened, and crumbly, it warrants a repeat test due to the prevalence of false-negative results in these tests.

• #2 Onychomycosis – Dermatologic Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/dermatologic-disorders/nail-disorders/onychomycosis

  Onychomycosis is fungal infection of the nail plate, nail bed, or both. Diagnosis is by appearance, wet mount, culture, polymerase chain reaction, or a combination. […] Onychomycosis is suspected by appearance in patients who also have tinea pedis; predictive clinical features include involvement of the 3rd or 5th toenail, involvement of the 1st and 5th toenails on the same foot, and unilateral nail deformity. […] Differentiation from psoriasis or lichen planus is important because the therapies differ, so diagnosis is typically confirmed by microscopic examination and, unless microscopic findings are conclusive, culture of scrapings or PCR of clippings. […] Although more expensive, PCR has become a more common technique to confirm the diagnosis of onychomycosis, especially if cultures are negative or a definitive diagnosis is required. […] Obtaining an adequate sample of nail for culture can be difficult because the distal subungual debris, which is easy to sample, often does not contain living fungus.

• #2 Onychomycosis – Wikipedia

  https://en.wikipedia.org/wiki/Onychomycosis

  The diagnosis is generally suspected based on the appearance and confirmed by laboratory testing. […] The four main tests are a potassium hydroxide smear, culture, histology examination, and polymerase chain reaction. […] Nail plate biopsy with periodic acid-Schiff stain appear more useful than culture or direct KOH examination. […] To reliably identify nondermatophyte molds, several samples may be necessary.

• #2 Molecular Testing for Nail Fungus Yields Improved Outcomes – AAPC Knowledge Center

  https://www.aapc.com/blog/48874-molecular-testing-for-nail-fungus-yields-improved-outcomes/?srsltid=AfmBOooNWrJFerb6vQEiLlffOLV9m5KbkMBacblDdgZZsH1EwMiqg2FY

  Onychomycosis (tinea unguium), or fungal infection of the nail, causes almost half of all nail pathologies worldwide. […] Heres why molecular testing is medically necessary for proper diagnosis and quality care, and how to prove it to the patients payer. […] Onychomycosis is an infection requires proper and specific diagnosis and treatment. […] Failure to initiate appropriate anti-fungal therapy in a timely manner has been associated with poor clinical outcomes and increased mortality. […] Conventional laboratory diagnosis of onychomycosis routinely involves only direct microscopic examination (potassium hydroxide (KOH) preparation) of the clinical specimen to determine the presence of fungi; however, this does not identify genus, species, or the specific pathogen (disease-causing fungus), nor does it differentiate between yeasts and molds.

• #2 Onychomycosis causes, symptoms and treatment – TeleMed2U

  https://www.telemed2u.com/dermatology/onychomycosis

  It is diagnosed by examining the nails. Your doctor may take nail clippings or scrape some of the debris from under your nail and send it to a laboratory for analysis. A diagnosis is important because psoriasis can look like nail fungus. Yeast and bacteria can also cause nail infections. Identifying the exact fungi thats causing the infection helps determine the best treatment for your needs.

• #2 Toenail Fungus (Onychomycosis/Tinea Unguium): Symptoms & Causes

  https://my.clevelandclinic.org/health/diseases/11303-toenail-fungus

  Toenail fungus is a widespread fungal infection that affects your toenails. […] Your healthcare provider will first look closely at the affected toenail to evaluate your symptoms. They may be able to identify toenail fungus simply by looking at your toe. However, your provider may order tests to confirm a fungal infection. […] Your healthcare provider will probably take a small sample from underneath your nail to further analyze it. Viewing the cells under a microscope can confirm a toenail fungus diagnosis. If the initial test is negative, a scraping can be sent to see if the fungus grows out in a culture. This also helps your healthcare provider identify the type of fungus. […] Toenail fungus is notoriously tricky to treat. You may need to treat tinea unguium for several months to get rid of the fungus. Still, toenail fungus often comes back.

• #3 Onychomycosis: Rapid Evidence Review | AAFP

  https://www.aafp.org/pubs/afp/issues/2021/1000/p359.html

  Onychomycosis should be suspected in patients with discolored nails, nail plate thickening, nail separation, and foul-smelling nails. […] Accurate diagnosis is important before initiating treatment because therapy is lengthy and can cause adverse effects. […] A potassium hydroxide preparation with confirmatory fungal culture, periodic acidSchiff stain, or polymerase chain reaction is the preferred diagnostic approach if confirmative testing is cost prohibitive or not available. […] Laboratory confirmation of nail infection is important for accurate diagnosis. […] A potassium hydroxide (KOH) preparation with direct microscopy is the preferred diagnostic method because it is highly specific, has rapid results, and is cost-effective. […] Diagnosis by KOH preparation alone is sufficient for treatment initiation. However, if KOH results are negative and there is high clinical suspicion for onychomycosis, other testing may be performed to confirm the diagnosis. […] Diagnostic testing is generally recommended before initiating treatment, but empiric treatment with terbinafine can be considered if testing is cost prohibitive.

• #3 Toenail Fungus (Onychomycosis/Tinea Unguium): Symptoms & Causes

  https://my.clevelandclinic.org/health/diseases/11303-toenail-fungus

  Toenail fungus is a widespread fungal infection that affects your toenails. […] Your healthcare provider will first look closely at the affected toenail to evaluate your symptoms. They may be able to identify toenail fungus simply by looking at your toe. However, your provider may order tests to confirm a fungal infection. […] Your healthcare provider will probably take a small sample from underneath your nail to further analyze it. Viewing the cells under a microscope can confirm a toenail fungus diagnosis. If the initial test is negative, a scraping can be sent to see if the fungus grows out in a culture. This also helps your healthcare provider identify the type of fungus. […] Toenail fungus is notoriously tricky to treat. You may need to treat tinea unguium for several months to get rid of the fungus. Still, toenail fungus often comes back.

• #3 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicy/external-policies/onychomycosis-testing/

  To screen for, diagnose, or confirm onychomycosis, attenuated total-reflectance fourier transform infrared (ATR-FTIR) spectroscopy is considered NOT MEDICALLY NECESSARY. […] Testing for the presence of fungal-derived sterols (e.g., ergosterol) is considered NOT MEDICALLY NECESSARY. […] Proprietary Testing An onychomycosis diagnosis should be given based on both clinical results and mycological lab results. Several types of tests have been developed to diagnose onychomycosis. The current diagnostic gold standard includes direct microscopy with potassium hydroxide (KOH) and fungal culture, as these methods can identify the pathogenic species and fungal viability; additional tests include polymerase chain reaction (PCR) testing, fluorescent staining and periodic acid-Schiff (PAS) staining. It has been reported that KOH testing is only 60% sensitive and cannot identify the species, but it can differentiate between dermatophytes and saprophytes based on a positive result; Currently, the most sensitive test (95%) is a pathologist interpreted nail clip biopsy that has been stained with periodic acid-Schiff (PAS) plus Grocott methenamine silver. Mycologic culture may be used for suspected onychomycosis cases with negative KOH results if spores, hyphae, or other fungal structures were seen via microscopy; histologic evaluation of a nail clipping using PAS stain may assist in an onychomycosis diagnosis with more sensitive results than those given by mycologic culture. An Aspergillus species causative agent may be suspected with a negative culture result but a positive KOH test. Fungal cultures must be interpreted by a mycologist and, while they are specific, they are only about 60% sensitive and take several weeks to grow. When utilized together, fungal culture and PCR can determine the source of the infection; the addition of PCR can improve species detection by 20% and will assist in differentiating between onychomycosis and nail dystrophy. PCR, when used with fungal culture, allows for a much faster, highly sensitive, and very specific diagnosis. Multiplex qPCR assays have shown to be reliable for onychomycosis diagnostics with a shorter response time than traditional culture methods.

• #3 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicyhb/external-policies/onychomycosis-testing/

  To screen for, diagnose, or confirm onychomycosis, attenuated total-reflectance fourier transform infrared (ATR-FTIR) spectroscopy is considered NOT MEDICALLY NECESSARY. […] Testing for the presence of fungal-derived sterols (e.g., ergosterol) is considered NOT MEDICALLY NECESSARY. […] An onychomycosis diagnosis should be given based on both clinical results and mycological lab results. […] Several types of tests have been developed to diagnose onychomycosis. The current diagnostic gold standard includes direct microscopy with potassium hydroxide (KOH) and fungal culture, as these methods can identify the pathogenic species and fungal viability; additional tests include polymerase chain reaction (PCR) testing, fluorescent staining and periodic acid-Schiff (PAS) staining. […] It has been reported that KOH testing is only 60% sensitive and cannot identify the species, but it can differentiate between dermatophytes and saprophytes based on a positive result; Currently, the most sensitive test (95%) is a pathologist interpreted nail clip biopsy that has been stained with periodic acid-Schiff (PAS) plus Grocott methenamine silver.

• #3 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicy/external-policies/onychomycosis-testing/

  Finally, the BAD also stated that histopathological analysis using periodic acid-Schiff staining is more sensitive than direct microscopy or culture. However, this technique is not currently available in the majority of dermatology clinics or mycology laboratories. Other diagnostic techniques under investigation include flow cytometry and confocal and scanning electron microscopy.

• #3 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicy/external-policies/onychomycosis-testing/

  Further, the BAD also stated that Traditionally, laboratory detection and identification of dermatophytes consists of culture and microscopy, which yields results within approximately two to six weeks. Calcofluor white is exceedingly useful for direct microscopic examination of nail specimens, as the fungal elements are seen much more easily than with potassium hydroxide, thereby increasing sensitivity. […] More recent molecular genetic tools were also highlighted as a newer diagnostic technique for the detection of dermatophytes. Regarding PCR testing, the BAD has stated that Realtime polymerase chain reaction (PCR) assays have been developed, which simultaneously detect and identify the most prevalent dermatophytes directly in nail, skin and hair samples and have a turnaround time of two days. It appears that realtime PCR significantly increased the detection rate of dermatophytes compared with culture. However, PCR may detect nonpathogenic or dead fungus, which could limit its use in identifying the true pathogen. Restriction fragment length polymorphism analysis, which identifies fungal ribosomal DNA, is very helpful for defining whether the disease is caused by repeat infection or another fungal strain when there is a lack of response to treatment. However, this technique has not been implemented into routine clinical practice.

• #3

  https://bpac.org.nz/BT/2011/March/fungal-infections.aspx

  Fungal infections of the skin, nails and hair are caused by dermatophytes. […] Diagnosis of a fungal infection is often made by clinical appearance alone, but sometimes laboratory examination of skin scrapings, hair or nail cuttings can help when the diagnosis is uncertain. […] Specimens should be sent to confirm disease when the infection is chronic, severe or when considering systemic therapy. Laboratory fungal testing is also justifiable in the following circumstances: To confirm fungal infection before starting on oral treatment, e.g. if the patient has been treating the lesion with topical steroids or a fungal infection involving the hair, palms of the hands or soles of the feet. […] Nail cuttings should also be collected. […] A negative culture result may arise due to: Feature of methodology, Incorrect initial clinical diagnosis, Sampling errors associated with poor collection technique, Sampling errors associated with inadequate specimen, The presence of non-viable hyphae elements in the distal region of a nail, An uneven colonisation of a nail with the fungus, Overgrowth by contaminant saprophytic fungi, Anti-fungal treatment used prior to collection of the specimen, A delay in the specimen reaching the laboratory, Incorrect laboratory procedures, Slow growth of the organism.

• #4 Fungal nail infection: diagnosis and management | The BMJ

  https://www.bmj.com/content/348/bmj.g1800

  Friable nail plate and nail spikes (yellow hyperkeratotic bands) suggest onychomycosis […] Histopathology of nail clippings can be done easily and quickly and is an economical way to establish a pathogenic role of fungi; specimens can be sent without fixatives or transport medium and results are available in 3-5 days […] Treatment should not be started before confirmation of infection by mycology […] False negative rates for culture are 30%; therefore a negative test result cannot exclude infection and should be repeated if clinical suspicion is high […] Consider non-dermatophyte moulds if onychomycosis is unresponsive to antifungals, and if microscopy provides a positive result but cultures give negative results.

• #4 Onychomycosis: Rapid Evidence Review | AAFP

  https://www.aafp.org/pubs/afp/issues/2021/1000/p359.html

  Onychomycosis should be suspected in patients with discolored nails, nail plate thickening, nail separation, and foul-smelling nails. […] Accurate diagnosis is important before initiating treatment because therapy is lengthy and can cause adverse effects. […] A potassium hydroxide preparation with confirmatory fungal culture, periodic acidSchiff stain, or polymerase chain reaction is the preferred diagnostic approach if confirmative testing is cost prohibitive or not available. […] Laboratory confirmation of nail infection is important for accurate diagnosis. […] A potassium hydroxide (KOH) preparation with direct microscopy is the preferred diagnostic method because it is highly specific, has rapid results, and is cost-effective. […] Diagnosis by KOH preparation alone is sufficient for treatment initiation. However, if KOH results are negative and there is high clinical suspicion for onychomycosis, other testing may be performed to confirm the diagnosis. […] Diagnostic testing is generally recommended before initiating treatment, but empiric treatment with terbinafine can be considered if testing is cost prohibitive.

• #5 Onychomycosis Testing

  https://www.southcarolinablues.com/web/public/brands/medicalpolicy/external-policies/onychomycosis-testing/

  The CDC remarks that an onychomycosis infection may be diagnosed through visual inspection, questioning the patient on their symptoms, or a fungal culture. The CDC states healthcare providers may take a small skin scraping or nail sample for testing. […] The CDC also notes that the term onychomycosis is the technical term for a fungal nail infection. It can be caused by ringworm or by infection with other types of fungi such as yeasts. Onychomycosis can affect the fingernails or toenails, but onychomycosis of the toenails is more common. […] Within the AAPs Red Book, recommendations include the following concerning diagnostic testing for onychomycosis: Fungal infection of the nail (tinea unguium or onychomycosis) can be verified by direct microscopic examination with potassium hydroxide, fungal culture of desquamated subungual material, or fungal stain of a nail clippings fixed in formalin.

• #5 Diagnosing and Treating Nail Fungus – MD Atlanta

  https://mdatl.com/2015/01/diagnosing-treating-nail-fungus/

  If the fungal culture returns negative, be sure the patient has not used topical antifungal preparation prior to the culture. Taking a second culture for fungus of the nails is helpful. If the second culture is negative, the problem may not be nail fungus. […] The differential diagnosis of nail fungus includes psoriasis, lichen planus, squamous cell carcinoma, verruca, and other eczematous dermatosis. […] If the nail culture is negative on two samples, consider a podiatry or dermatology consultation. If the nail is painful, bleeding or shows erythema, it may be important to send the patient for a nail bed biopsy. […] Treatment of nail fungus is challenging. The toenail grows slowly, only 1mm per month, fully regrowing in 12 to 18 months. The fingernail may regrow in six months. […] Oral medications are not always effective, have systemic risk and may interact with other medications.

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