Materiały źródłowe

• #1 Brain Abscess – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK441841/

  A brain abscess is a localized area of necrosis within the brain parenchyma, often resulting from infectious agents, such as Staphylococcus and Streptococcus, or trauma or surgery. In addition, infections in the head and neck may contribute to abscess development. Abscesses often arise from local infections in areas such as the ear, teeth, sinuses, mastoid air cells, or epidural spaces, but they may also originate from distant sites such as the lungs or heart. In young children, congenital heart disease can be a risk factor. […] Brain abscesses can originate locally and spread to other parts of the body. They often form from infections in nearby areas, such as the ear or sinuses, and may occasionally extend from more distant sites, such as the lungs or heart. […] Infections in the head and neck region can lead to the development of brain abscesses. Otitis media (5%) and mastoiditis are associated with abscesses in the inferior temporal lobe and cerebellum. Paranasal sinus infections account for 30% to 50% of cases, frequently leading to brain abscesses development. Infections from the frontal or ethmoid sinuses may spread to the frontal lobes, while dental infections commonly result in frontal lobe abscesses.

• #1

  https://www.nhs.uk/conditions/brain-abscess/

  A brain abscess is a pus-filled swelling in the brain. It usually occurs when bacteria or fungi enter the brain tissue after an infection or severe head injury. […] There are 3 main ways a brain abscess can develop. These are: an infection in another part of the skull such as an ear infection, sinusitis or dental abscess, which can spread directly into the brain; an infection in another part of the body for example, the infection that causes pneumonia spreading into the brain via the blood; trauma, such as a head injury that cracks open the skull, allowing bacteria or fungi to enter the brain. […] However, in some cases, the source of the infection remains unknown.

• #1 Pathogenesis, clinical manifestations, and diagnosis of brain abscess – UpToDate

  https://www.uptodate.com/contents/pathogenesis-clinical-manifestations-and-diagnosis-of-brain-abscess

  Brain abscess is a focal infectious collection within the brain parenchyma, which can arise as a complication of another infection or through trauma or surgery. […] Bacteria can invade the brain either by direct spread or through hematogenous seeding. Direct spread accounts for 25 to 50 percent of cases. The location reflects the site of the primary infection that spreads to the cerebral cortex. These locations, in order of decreasing frequency, are: the frontal or temporal lobes; frontal-parietal region; parietal lobe; cerebellum; and occipital lobe. Bacteremic spread typically causes multiple lesions. No primary site or underlying condition can be identified in 10 to 35 percent of patients with brain abscess depending upon the series. […] Tissue damage seen in brain abscess is primarily caused by the host’s acute inflammatory response to the invading pathogen.

• #1 Brain Abscess: Background, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/212946-overview

  Intracranial abscesses can originate from infection of contiguous structures (eg, otitis media, dental infection, mastoiditis, sinusitis) secondary to hematogenous spread from a remote site (especially in patients with cyanotic congenital heart disease), after skull trauma or surgery, and, rarely, following meningitis. In at least 15% of cases, no source can be identified. […] The most frequent causative pathogens in community-acquired brain abscess are oral cavity bacteria such as Streptococcus anginosus group, Fusobacterium spp, and Aggregatibacter spp, which are often associated with dental and chronic ear infections. Other less common etiologies include Staphylococcus aureus and Gram-negative bacilli in post-neurosurgical brain abscess, Mycobacterium tuberculosis in endemic areas, and Nocardia spp, fungi, and parasites in the severely immune-compromised.

• #1 Brain Abscess – Neurologic Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/neurologic-disorders/brain-infections/brain-abscess

  A brain abscess can result from […] Direct extension of cranial infections (eg, osteomyelitis, mastoiditis, sinusitis, subdural empyema) […] Penetrating head wounds (including neurosurgical procedures) […] Hematogenous spread (eg, in bacterial endocarditis, congenital heart disease with right-to-left shunt, or IV drug use) […] Unknown causes […] The bacteria involved are usually anaerobic and sometimes mixed, often including anaerobes, such as Bacteroides and anaerobic and microaerophilic streptococci. Staphylococci are commonly involved after cranial trauma, neurosurgery, or endocarditis. Enterobacteriaceae may be isolated in chronic ear infections. After chronic suppurative otitis media, anaerobic bacteria, streptococci, and gram-negative bacteria are common causes.

• #1 Brain Abscess Clinical Presentation: History, Physical, Causes

  https://emedicine.medscape.com/article/212946-clinical

  The microbial etiology of brain abscess depends on the patient’s age, site of primary infection, and the patient’s immune status. […] Anaerobic and microaerophilic cocci and gram-negative and gram-positive anaerobic bacilli are the most important isolates. A significant number of brain abscesses are polymicrobic. […] Oral flora anaerobes generally originate from infected ears and sinuses and abdominal anaerobes (Bacteroides fragilis group) reach the intracranial cavity through bacteremia. […] The predominant organisms include the following: Staphylococcus aureus, including methicillin-resistant; Aerobic, anaerobic, and microaerophilic streptococci, including alpha-hemolytic streptococci, Streptococcus anginosus (milleri) group (Streptococcus anginosus, Streptococcus constellatus, and Streptococcus intermedius); Prevotella and Fusobacterium species and B fragilis; Enterobacteriaceae (Klebsiella pneumoniae, Escherichia coli, Enterobacter species, and Proteus species); Pseudomonas species; Other anaerobes: (Veillonella, Eubacterium, Cutibacterium (formerly Propionibacterium), Methanobrevibacter oralis, Methanobrevibacter smithii.

• #1 Brain Abscess – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK441841/

  Infectious hematogenous seeding of the brain can arise from various conditions, with the lungs being the most common source. Pulmonary infections, including lung abscesses and empyemas, are frequently seen in individuals with bronchiectasis, and cystic fibrosis is a significant contributing factor. […] In children, cyanotic congenital heart disease accounts for over 60% of brain abscess cases. Other identified causative factors include bacterial endocarditis, ventricular aneurysms, and thrombosis. Skin, pelvic, and intra-abdominal infections are also commonly reported risk factors. […] The most commonly isolated microbial pathogens in brain abscesses are staphylococci and streptococci, with Staphylococcus aureus and viridans streptococci being the most prevalent bacterial species. […] A meta-analysis of 9699 patients from 123 studies identified the following list of causative pathogens in brain abscesses: Streptococcus species, Staphylococcus species, Enterococcus species, Gram-negative enteric bacteria, Actinomycetales species, Mycobacterium tuberculosis, and others.

• #1 Brain Abscess Clinical Presentation: History, Physical, Causes

  https://emedicine.medscape.com/article/212946-clinical

  Al Masalma et al performed a 16S rDNA-based metagenomic analysis of cerebral abscesses and identified 80 distinct bacterial taxa, including 44 not previously described in brain abscess. Therefore, microbial flora of brain abscesses is far from being fully known and is differentially distributed depending on the abscess etiology. Further studies are warranted to determine the significance of the identification of the newly recovered bacteria associated within brain abscesses.

• #1 Brain Abscess Clinical Presentation: History, Physical, Causes

  https://emedicine.medscape.com/article/212946-clinical

  The following organisms are associated with certain predisposing conditions: Sinus and dental infections – Aerobic and anaerobic streptococci, anaerobic gram-negative bacilli (eg, Prevotella, Porphyromonas, Bacteroides, Fusobacterium, Cutibacterium (formerly Propionibacterium), microaerophilic streptococci (mainly Streptococcus milleri), Haemophillus, S aureus, Enterobacteriaceae); Ear infections (including mastoiditis) – Aerobic and anaerobic streptococci, anaerobic gram-negative bacilli, Haemophillus, Pseudomonas, and Enterobacteriaceae; Pulmonary infections – Aerobic and anaerobic streptococci, anaerobic gram-negative bacilli (eg, Prevotella, Porphyromonas, Bacteroides), Fusobacterium, Actinomyces, Nocardia; Endocarditis – Alpha hemolytic streptococci, S aureus; Congenital heart disease – Aerobic and microaerophilic streptococci, S aureus; Liver abscess or diabetes mellitus (reported in Southeast Asia) – Klebsiella pneumoniae; Penetrating head trauma – S aureus, aerobic streptococci, Enterobacteriaceae, Clostridium spp.; Esophageal dilatation – Peptostrepotoccocci spp., Streptococcus milleri, and Escherichia coli; Neurosurgical procedures – S aureus, Pseudomonas, Enterobacter, Propionibacterium acnes; Neonates – Citrobacter; Urinary tract – Pseudomonas, Enterobacteriaceae, Enterobacter; Transplantation – Aspergillus, Candida, Cryptococcus, Mucorales, Nocardia, T gondii; Immunocompromised – Aerobic gram-negative bacilli, T gondii, Nocardia asteroids, Listeria monocytogenes, Aspergillus, Cryptococcus, Coccidioides immitis, Candida, Mucorales; HIV infection – T gondii, Mycobacterium, Cryptococcus, Nocardia, L monocytogenes; Living, visiting, or immigrating from an endemic area: Taenia solium (causing cysticercosis), Schistosoma japonicum, Entamoeba histolytica, and Paragonimus species.

• #1 Brain abscess Information | Mount Sinai – New York

  https://www.mountsinai.org/health-library/diseases-conditions/brain-abscess

  A brain abscess is a collection of pus, immune cells, and other material in the brain, caused by a bacterial or fungal infection. […] Brain abscesses commonly occur when bacteria or fungi infect part of the brain. As a result, swelling and irritation (inflammation) develop. Infected brain cells, white blood cells, live and dead bacteria or fungi collect in an area of the brain. Tissue forms around this area and creates a mass or abscess. […] The germs that cause a brain abscess can reach the brain through the blood. Or, they enter the brain directly, such as during brain surgery. In some cases, a brain abscess develops from an infection in the sinuses. […] The source of the infection is often not found. However, the most common identified source is a lung infection. Less often, a heart infection is the cause. […] The following raise your chance of developing a brain abscess: A weakened immune system (such as in people with HIV/AIDS), Chronic disease, such as cancer, Medicines that suppress the immune system (corticosteroids or chemotherapy), Congenital heart disease.

• #1

  https://journals.lww.com/neurosurgery/fulltext/9900/brain_abscess_causes_brain_damage_with.1436.aspx

  Bacterial brain abscesses may have long-term clinical consequences, eg, mental fatigue or epilepsy, but long-term structural consequences to the brain remain underexplored. […] A bacterial brain abscess results from a focal bacterial infection that leads to the formation of pus within the brain parenchyma. A brain abscess could damage brain tissue in several ways. First, an abscess may contain many milliliters of pus that may cause tissue displacement and distortion. Second, the abscess pus contains many neuroactive and neurotoxic substances at high concentrations, such as bacterial toxins, cytokines, glutamate, potassium, and ammonia. It is at present unclear to what extent the abscess capsule prevents these molecules from diffusing into the surrounding brain tissue. Third, the abscess capsule is replete with leukocytes and constitutes a site of inflammation that could cause neurotoxicity. Long-term complications of brain abscess include epilepsy, cognitive disturbances, and mental fatigue support the notion that brain abscesses may cause permanent brain dysfunction or damage.

• #1

  https://journals.lww.com/neurosurgery/fulltext/9900/brain_abscess_causes_brain_damage_with.1436.aspx

  The bigger a brain abscess is allowed to grow, the more extensive is the long-term focal reduction in brain activity. This finding emphasizes the need for rapid neurosurgical intervention. The abscess capsule does not display long-lasting inflammation and probably does not explain long-term symptoms after brain abscess.

• #1

  https://www.nhs.uk/conditions/brain-abscess/causes/

  A brain abscess is usually caused by infection with either bacteria or fungi. […] Infections spread through the blood can cause brain abscesses. […] People with a weakened immune system have a higher risk of developing a brain abscess from a blood-borne infection. […] Infections and health conditions that may cause a brain abscess include: cyanotic heart disease, pulmonary arteriovenous fistula, a dental abscess, lung infections, infections of the heart, skin infections, infections of the abdomen, pelvic infections. […] Direct trauma to the skull can also lead to a brain abscess. […] The most commonly reported causes include a skull fracture caused by a penetrating head injury and a gunshot or shrapnel wound.

• #1 Bacterial Brain Abscess

  https://pmc.ncbi.nlm.nih.gov/articles/PMC4212419/

  Etiology can be identified in many cases, but the source of infection remains unclear in a significant proportion of those with abscess even after a thorough investigation. […] Brain abscesses are often attributed to hematogenous spread, contiguous spread, recent neurosurgical procedure, or penetrating head trauma. […] Endocarditis or pulmonary infections (pneumonia, empyema, and abscess) are the most common sources of hematogenous spread. […] Cyanotic heart disease and pulmonary arteriovenous malformation are consistently reported in association with brain abscess. […] Hematogenous spread accounts for 9% to 43% of brain abscesses. […] Contiguous infection may result from primary dental, sinus, ear infections, or mastoiditis and represents 14% to 58% proportion of brain abscess. […] Invasive neurosurgical procedures are a known risk factor for development of brain abscess. […] Immunocompromise raises risk of CNS infection. […] A significant proportion of patients with appropriately treated abscess recover completely and can survive without significant neurologic sequelae.

• #1 Brain Abscess: Risk Factors, Symptoms & Diagnosis

  https://www.healthline.com/health/brain-abscess

  An abscess in the brain of an otherwise healthy person is usually caused by bacterial infection. Fungal brain abscesses tend to occur in people with weakened immune systems. […] A brain abscess forms when fungi, viruses, or bacteria reach your brain through a wound in your head or an infection somewhere else in your body. According to the Childrens Hospital of Wisconsin, infections from other parts of the body account for between 20 and 50 percent of all brain abscess cases. Heart and lung infections are among the most common causes of brain abscesses. However, brain abscesses can also begin from an ear or sinus infection, or even an abscessed tooth. […] Certain birth defects allow infections to reach the brain more easily through the teeth and intestines. One example of this is tetralogy of Fallot, which is a heart defect.

• #1 Brain Abscess: A Rare Intracranial Infection in Children | Pediatric Emergency Medicine

  https://www.acep.org/pediatrics/education/education-articles/brain-abscess-article

  Brain abscesses are focal parenchymal infections, most often occurring in the first two decades of life. The majority of abscesses occur from direct inoculation of infections including paranasal sinusitis, mastoiditis, dental infections, and otitis media, but also may occur from penetrating skull trauma, surgery (including implantation of ventriculoperitoneal shunts), and hematogenous seeding. A hematogenous source, in association with spread from a distant source including the skin, abdomen, pelvis, heart, and lung, occurs in up to 25% of cases. No primary source is found in approximately 20-30% of patients. Many different pathogens can cause brain abscesses and the microbial etiology is related to the site of primary infection. A single pathogen can be isolated in 70% of cases, and polymicrobial infections occur in 18% of cases. Overall, the most common pathogen identified is Streptococci. Peptostreptococcus, Bacteroides, and Streptococcus are usually diagnosed in patients with sinusitis and otitis media. Streptococci viridans and Staphlococcus aureus are most often isolated in patients with cardiac disease. Gram-negative rods (Bacteroides, Prevotella, Porphyromonas) and other aerobic gram-positive cocci are seen in patients with prior neurosurgery or head trauma. Fungal causes including Candida, Aspergillus, and Cryptococcus are most common in immunocompromised children. […] The treatment of brain abscesses requires a multimodality approach, consisting of surgical evacuation, long-term antibiotic treatment, and treatment of another primary infection if present.

• #1 Brain Abscess | Oncohema Key

  https://oncohemakey.com/brain-abscess/

  The development of a brain abscess in the setting of neonatal meningitis deserves special comment. […] In hematogenous cases, the polycythemia and systemic hypoxia observed in CCHD and hereditary hemorrhagic telangiectasia increase blood viscosity, with an associated reduction in brain capillary flow, perhaps leading to microinfarction and reduced tissue oxygenation in the brain.

• #1 SciELO Brazil – Brain abscess following ischemic stroke with secondary hemorrhage Brain abscess following ischemic stroke with secondary hemorrhage

  https://www.scielo.br/j/anp/a/zvrc8yFtpSvqqCRMntMbf9D/?lang=en

  Cerebral vascular events constitute the most common group of neurological diseases, and are usually followed by systemic infections, being pneumonia, urinary tract infection and sepsis the most frequent. Brain abscess compromising the infarcted cerebral tissue is a rare condition. It most frequently happens a few weeks after an infectious systemic insult, which had usually followed the ischemic stroke. […] Cerebral ischemia is considered to be a predisposing factor for the genesis of brain abscess after stroke. Due to impaired cerebral oxigenation and blood brain barrier disruption in the infarcted area, the formation of an abscess becomes feasible following bacteremia, a fact that has recently caught the attention of neurologists and neurosurgeons. […] The pathogenesis of brain abscess over an infarcted area involves previous local brain damage and a distant focus of infection. The vascular event, ischemic or hemorrhagic, produces local blood brain barrier disruption, which makes this region vulnerable to microbial seeding in the event of bacteremia secondary to systemic infection, leading to the formation of cerebral abscess. Staphylococcus aureus is reported in the literature as the most frequent etiologic agent. In this report, patient had a respiratory tract infection caused by Pseudomonas aeruginosa and Staphylococcus aureus, blood culture positive for anaerobic gram-positive cocci in chains, and Streptococcus sp isolated in the abscess secretion. Brain abscess developed five weeks after the stroke, although it took longer to be diagnosed in more than 70% of the cases reported in the literature. The reduced delivery of antibiotics to ischemic areas decreases the effectiveness of treatment and prolongs its course.

• #1

  https://continentalhospitals.com/diseases/parasitic-brain-abscess/

  Parasitic brain abscess is a serious medical condition that requires immediate attention. It refers to the formation of an abscess, or a collection of pus, within the brain as a result of an infection caused by parasites. […] Parasites that commonly cause brain abscesses include Toxoplasma gondii, Taenia solium (tapeworm), and Entamoeba histolytica. These parasites can enter the body through various routes such as ingestion of contaminated food or water, contact with infected animals, or through insect bites. […] One common cause of parasitic brain abscesses is the presence of certain parasites in the body. These parasites can enter the bloodstream through various means, such as contaminated food or water, insect bites, or direct contact with infected individuals or animals. Once inside the body, they can travel to the brain and cause an abscess to form.

• #1

  https://continentalhospitals.com/diseases/parasitic-brain-abscess/

  Another potential cause is a weakened immune system. Individuals with compromised immune systems, such as those with HIV/AIDS or undergoing immunosuppressive therapy, are at a higher risk of developing parasitic brain abscesses. […] Additionally, certain medical procedures or conditions can increase the likelihood of developing a parasitic brain abscess. For example, invasive surgeries that involve entering the skull may introduce pathogens into the brain if proper precautions are not taken. […] Similarly, individuals with underlying conditions such as cysticercosis (caused by tapeworm infection) or toxoplasmosis (caused by Toxoplasma gondii parasite) have an increased susceptibility to developing these abscesses. […] It is important to note that prevention plays a crucial role in reducing the risk of parasitic brain abscesses. Practicing good hygiene, avoiding consumption of contaminated food and water sources, and taking appropriate precautions during medical procedures are all measures that can help minimize exposure to potential causative agents.

• #1 Infectious brain abscesses and granulomas: analysis of 110 episodes in adults | BMC Neurology | Full Text

  https://bmcneurol.biomedcentral.com/articles/10.1186/s12883-024-03953-0

  The causative pathogens of brain abscesses and infectious granulomas included Mycobacterium tuberculosis, Escherichia coli, and Mucorales, each in four (3.6%), and Staphylococcus aureus and Pseudomonas species, each in three (2.7%) cases. […] The low proportion of patients in our study who had microbiological confirmation of the causative agent of their brain abscesses or granulomas is also a notable finding that warrants discussion. Only a minority of cases (about 26% for abscess culture and 15% for blood culture) yielded positive results, indicating a considerable diagnostic challenge in identifying the specific pathogens responsible for these infections. […] The findings of our study regarding the causative pathogens of brain abscesses and infectious granulomas reflect a significant deviation from previous reports, suggesting a possible shifting microbial landscape in this clinical entity. […] The shift in our study might mirror alterations in patient demographics or underlying conditions. […] The findings underscore the relationship between specific comorbidities and patterns of brain abscess formation, revealing a complex interplay in their distribution.

• #2

  https://journals.lww.com/neurosurgery/fulltext/9900/brain_abscess_causes_brain_damage_with.1436.aspx

  Bacterial brain abscesses may have long-term clinical consequences, eg, mental fatigue or epilepsy, but long-term structural consequences to the brain remain underexplored. […] A bacterial brain abscess results from a focal bacterial infection that leads to the formation of pus within the brain parenchyma. A brain abscess could damage brain tissue in several ways. First, an abscess may contain many milliliters of pus that may cause tissue displacement and distortion. Second, the abscess pus contains many neuroactive and neurotoxic substances at high concentrations, such as bacterial toxins, cytokines, glutamate, potassium, and ammonia. It is at present unclear to what extent the abscess capsule prevents these molecules from diffusing into the surrounding brain tissue. Third, the abscess capsule is replete with leukocytes and constitutes a site of inflammation that could cause neurotoxicity. Long-term complications of brain abscess include epilepsy, cognitive disturbances, and mental fatigue support the notion that brain abscesses may cause permanent brain dysfunction or damage.

• #2 Brain Abscess – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK441841/

  A brain abscess is a localized area of necrosis within the brain parenchyma, often resulting from infectious agents, such as Staphylococcus and Streptococcus, or trauma or surgery. In addition, infections in the head and neck may contribute to abscess development. Abscesses often arise from local infections in areas such as the ear, teeth, sinuses, mastoid air cells, or epidural spaces, but they may also originate from distant sites such as the lungs or heart. In young children, congenital heart disease can be a risk factor. […] Brain abscesses can originate locally and spread to other parts of the body. They often form from infections in nearby areas, such as the ear or sinuses, and may occasionally extend from more distant sites, such as the lungs or heart. […] Infections in the head and neck region can lead to the development of brain abscesses. Otitis media (5%) and mastoiditis are associated with abscesses in the inferior temporal lobe and cerebellum. Paranasal sinus infections account for 30% to 50% of cases, frequently leading to brain abscesses development. Infections from the frontal or ethmoid sinuses may spread to the frontal lobes, while dental infections commonly result in frontal lobe abscesses.

• #2 Bacterial Brain Abscess

  https://pmc.ncbi.nlm.nih.gov/articles/PMC4212419/

  Etiology can be identified in many cases, but the source of infection remains unclear in a significant proportion of those with abscess even after a thorough investigation. […] Brain abscesses are often attributed to hematogenous spread, contiguous spread, recent neurosurgical procedure, or penetrating head trauma. […] Endocarditis or pulmonary infections (pneumonia, empyema, and abscess) are the most common sources of hematogenous spread. […] Cyanotic heart disease and pulmonary arteriovenous malformation are consistently reported in association with brain abscess. […] Hematogenous spread accounts for 9% to 43% of brain abscesses. […] Contiguous infection may result from primary dental, sinus, ear infections, or mastoiditis and represents 14% to 58% proportion of brain abscess. […] Invasive neurosurgical procedures are a known risk factor for development of brain abscess. […] Immunocompromise raises risk of CNS infection. […] A significant proportion of patients with appropriately treated abscess recover completely and can survive without significant neurologic sequelae.

• #2 Brain abscess: Symptoms, causes, diagnosis, treatment

  https://www.medicalnewstoday.com/articles/185619

  A brain abscess is most likely to result from a bacterial or fungal infection in some part of the brain. Parasites can also cause an abscess. […] When the bacteria, fungi, or parasites infect part of the brain, inflammation and swelling occur. In these cases, the abscess will consist of infected brain cells, active and dead white blood cells, and the organisms that cause the problem. […] Between 9 and 43 percent of abscesses result from pathogens that traveled from another part of the body. […] Many bacterial brain abscesses stem from a lesion somewhere else in the body. It is crucial to find that primary lesion, or there may be a repeat infection in the future. […] The most common infections known to cause brain abscesses are: endocarditis, an infection of the heart valve; pneumonia, bronchiectasis, and other lung infections and conditions; abdominal infections, such as peritonitis, an inflammation of the inner wall of the abdomen and pelvis; cystitis, or inflammation of the bladder, and other pelvic infections. […] An infection can spread from a nearby area, and this accounts for 14-58 percent of brain abscesses. […] A brain abscess can result from trauma, such as from neurological surgery or a penetrating brain injury.

• #2 Brain Abscess Clinical Presentation: History, Physical, Causes

  https://emedicine.medscape.com/article/212946-clinical

  The microbial etiology of brain abscess depends on the patient’s age, site of primary infection, and the patient’s immune status. […] Anaerobic and microaerophilic cocci and gram-negative and gram-positive anaerobic bacilli are the most important isolates. A significant number of brain abscesses are polymicrobic. […] Oral flora anaerobes generally originate from infected ears and sinuses and abdominal anaerobes (Bacteroides fragilis group) reach the intracranial cavity through bacteremia. […] The predominant organisms include the following: Staphylococcus aureus, including methicillin-resistant; Aerobic, anaerobic, and microaerophilic streptococci, including alpha-hemolytic streptococci, Streptococcus anginosus (milleri) group (Streptococcus anginosus, Streptococcus constellatus, and Streptococcus intermedius); Prevotella and Fusobacterium species and B fragilis; Enterobacteriaceae (Klebsiella pneumoniae, Escherichia coli, Enterobacter species, and Proteus species); Pseudomonas species; Other anaerobes: (Veillonella, Eubacterium, Cutibacterium (formerly Propionibacterium), Methanobrevibacter oralis, Methanobrevibacter smithii.

• #2 Brain Abscess – The NeuroMedical Center

  https://www.theneuromedicalcenter.com/for-patients/patient-resources/conditions/brain-abscess/

  Brain Abscesses are pockets of pus in your brain. Tissue has grown around it, walling it off from the rest of your body. An abscess in the brain of an otherwise healthy person is usually caused by bacterial infection. Germs can get into your brain during surgery or in through a head wound. Fungal brain abscesses tend to occur in people with weakened immune systems. […] Certain groups of people are at a higher risk than others. Some diseases, disorders, and conditions that raise your risk include: A Compromised Immune System Due to HIV or AIDs, Cancer or Chronic Illness, Congenital Heart Disease, Major Head Injury or Skull Fracture, Meningitis, Chemotherapy Drugs, Chronic Sinus or Middle Ear Infections.

• #2 Pathogenesis, clinical manifestations, and diagnosis of brain abscess – UpToDate

  https://www.uptodate.com/contents/pathogenesis-clinical-manifestations-and-diagnosis-of-brain-abscess

  Brain abscess is a focal infectious collection within the brain parenchyma, which can arise as a complication of another infection or through trauma or surgery. […] Bacteria can invade the brain either by direct spread or through hematogenous seeding. Direct spread accounts for 25 to 50 percent of cases. The location reflects the site of the primary infection that spreads to the cerebral cortex. These locations, in order of decreasing frequency, are: the frontal or temporal lobes; frontal-parietal region; parietal lobe; cerebellum; and occipital lobe. Bacteremic spread typically causes multiple lesions. No primary site or underlying condition can be identified in 10 to 35 percent of patients with brain abscess depending upon the series. […] Tissue damage seen in brain abscess is primarily caused by the host’s acute inflammatory response to the invading pathogen.

• #2 Study identifies potential link between oral bacteria and brain abscesses | British Dental Journal

  https://www.nature.com/articles/s41415-022-5417-x

  Bacteria known to cause oral infections may also be a contributory factor in patients developing potentially life-threatening abscesses on the brain, new research has shown. […] The study, published in the Journal of Dentistry, investigated brain abscesses and their association with bacteria that occur in the oral cavity. […] Their results showed that the 52 patients where no cause had been found were about three times as likely to have oral bacteria present in their samples. […] Those patients also carried significantly higher counts of Streptococcus anginosus, a bacterium that can lead to pharyngitis, bacteraemia, and infections in internal organs such as the brain, lung, and liver. […] Writing in the study, researchers say the findings suggest that the oral cavity could be considered a source of infection in cases of brain abscess where no clear cause has been identified. […] However, it was still surprising to frequently find orally occurring bacteria in brain abscesses of unexplained origin.

• #2 Brain Abscess: Risk Factors, Symptoms & Diagnosis

  https://www.healthline.com/health/brain-abscess

  An abscess in the brain of an otherwise healthy person is usually caused by bacterial infection. Fungal brain abscesses tend to occur in people with weakened immune systems. […] A brain abscess forms when fungi, viruses, or bacteria reach your brain through a wound in your head or an infection somewhere else in your body. According to the Childrens Hospital of Wisconsin, infections from other parts of the body account for between 20 and 50 percent of all brain abscess cases. Heart and lung infections are among the most common causes of brain abscesses. However, brain abscesses can also begin from an ear or sinus infection, or even an abscessed tooth. […] Certain birth defects allow infections to reach the brain more easily through the teeth and intestines. One example of this is tetralogy of Fallot, which is a heart defect.

• #2 Brain abscess Information | Mount Sinai – New York

  https://www.mountsinai.org/health-library/diseases-conditions/brain-abscess

  A brain abscess is a collection of pus, immune cells, and other material in the brain, caused by a bacterial or fungal infection. […] Brain abscesses commonly occur when bacteria or fungi infect part of the brain. As a result, swelling and irritation (inflammation) develop. Infected brain cells, white blood cells, live and dead bacteria or fungi collect in an area of the brain. Tissue forms around this area and creates a mass or abscess. […] The germs that cause a brain abscess can reach the brain through the blood. Or, they enter the brain directly, such as during brain surgery. In some cases, a brain abscess develops from an infection in the sinuses. […] The source of the infection is often not found. However, the most common identified source is a lung infection. Less often, a heart infection is the cause. […] The following raise your chance of developing a brain abscess: A weakened immune system (such as in people with HIV/AIDS), Chronic disease, such as cancer, Medicines that suppress the immune system (corticosteroids or chemotherapy), Congenital heart disease.

• #2 Brain Abscess Clinical Presentation: History, Physical, Causes

  https://emedicine.medscape.com/article/212946-clinical

  Less common causes include the following: Haemophillus influenzae; Streptococcus pneumoniae; Neisseria meningitidis; Haemophilus aphrophilus; Other Enterobacteriacae; Burkholderia pseudomallei (also known as Pseudomonas pseudomallei); Actinobacillus actinomycetemcomitans; Actinomyces; Nocardia asteroides; Mycobacterium species; Fungi (eg, Aspergillus, Candida, Cryptococcus, Mucorales, Coccidioides, Histoplasma capsulatum, Blastomyces dermatitidis, Bipolaris, Exophiala dermatitidis, Curvularia pallescense, Ochronosis gallopava, Ramichloridium mackenziei); Protozoa (eg, Toxoplasma gondii, Entamoeba histolytica, Trypanosoma cruzi, Schistosoma, Paragonimus); Helminths (eg, Taenia solium); Toxoplasma gondii; Pseudallescheria boydii. […] Co-infection with bacterial, viral, and fungal organisms can occur.

• #2 Brain Abscess: Risk Factors, Symptoms & Diagnosis

  https://www.healthline.com/health/brain-abscess

  If your abscess is deep inside your brain or its 2.5 centimeters or less, it will probably be treated with antibiotics. Antibiotic medications will also be used to treat any underlying infections that may have been the cause of the brain abscess. […] Surgery is often the next step if an abscess doesn’t get smaller with the use of antibiotics. It may also be the preferred treatment for abscesses greater than 2.5 centimeters wide. […] Knowing the cause of the infection will help your doctor find the most effective antibiotics. […] You can lower your risk by monitoring any conditions that can cause a brain abscess.

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