The genera Peptococcus and Peptostreptococcus were described by Kluyver and van Niel in They were separated on the basis of morphological characteristics:
Harrison, in Principles and Practice of Pediatric Infectious Diseases Fourth EditionEtiology Overall, gram-positive cocci are the most common pathogens of brain abscess. The Streptococcus milleri group S. Although Streptococcus pneumoniae commonly causes meningitis, it rarely causes brain abscess.
Citrobacter, Salmonella, Serratia, Proteus spp. Citrobacter koseri and Cronobacter sakazakii are associated with multifocal brain abscesses, and Cronobacter with powdered formula ingestion. Rarely, Mycoplasma or Ureoplasma species cause neonatal brain abscess. Chronic middle-ear infections, uncontrolled diabetes mellitus, and chemotherapy-induced neutropenia are risks for Pseudomonas aeruginosa.
Impaired cell-mediated immune function, e. Fungal brain abscesses occur with congenital or acquired neutrophil abnormalities, stem cell or solid organ transplantation, or poorly controlled acquired immunodeficiency syndrome AIDSparticularly after broad-spectrum antibacterial treatment.
Although Cryptococcus usually manifests as meningitis, it can cause brain abscess. Toxoplasma gondii commonly causes brain abscess in adults with AIDS, but is rare in children.
Entamoeba histolytica brain abscess is rare even with amebiasis. Other protozoa causing brain abscess include Acanthamoeba, Schistosoma, or Paragonimus spp. Helminthic migration Strongyloides stercoralis, Trichinella, or Taenia can cause brain abscesses or masses.
Neurocysticercosis is a relatively frequent cause of single or multiple central nervous system CNS masses that can be ring enhancing and can be misconstrued as bacterial brain abscesses among patients from endemic areas, e.
Table includes additional uncommon pathogens. Mycobacterium tuberculosis brain abscess differs from tuberculoma, which is a granulomatous mass containing epithelioid and giant cells.
Tuberculous abscesses are purulent collections containing acid-fast bacilli. Magnetic resonance imaging MRI differentiates these two conditions. Lesion location or distribution can suggest the pathogen. Frontal lobe abscess usually a complication of sinusitis suggests oral flora, i. Penetrating trauma increases the risk for Staphylococcus aureus increasingly methicillin-resistant S.
Temporal lobe or cerebellar abscesses suggest middle-ear pathogens in addition to oral flora mostly anaerobic and microaerophilic streptococci plus anaerobes, and less often Enterobacteriaceae. Hematogenous spread due to endocarditis, septic thrombophlebitis, lung abscess, pleural empyema, bronchiectasis in cystic fibrosisosteomyelitis, or skin infections classically produces multiple lesions in the distribution of the middle cerebral artery.
However, hematogenous abscesses can occur in any pattern. Common hematogenous pathogens are Staphylococcus aureus, aerobic or anaerobic streptococci, and rarely, Nocardia or Actinomyces spp. Clues to causative pathogens in subdural empyemas relate to the pathogenesis. In young children, subdural empyema usually accompanies bacterial meningitis; pathogens are Haemophilus influenzae type b Hibpneumococcus, or rarely meningococcus see Table Subdural empyemas not accompanying meningitis have the same pathogens as brain abscesses.
Aerobic and anaerobic streptococci e. Rare subdural pathogens include nontyphoid Salmonella, S.
Mycobacterium tuberculosis rarely causes subdural empyema. Gram-negative organisms are increasingly detected in both subdural empyema and epidural abscess. Pseudallescheria, Aspergillus, or Candida spp.
Spinal epidural abscess rarely is due to Brucella melitensis Middle Eastern and Mediterranean areaNocardia asteroids group, Actinomyces israelii, Cryptococcus neoformans, or Aspergillus. Epidural and other paravertebral abscess can complicate Bartonella henselae vertebral osteomyelitis.Start studying Pathogenic Gram-Positive Cocci.
Learn vocabulary, terms, and more with flashcards, games, and other study tools.
Pathogenic bacteria are bacteria that can cause disease. This article deals with human pathogenic bacteria. Although most bacteria are harmless or often beneficial, some are pathogenic, with the number of species estimated as fewer than that are seen to cause infectious diseases in humans.
. Pathogenic bacteria are bacteria that can cause disease. This article deals with human pathogenic bacteria. Although most bacteria are harmless or often beneficial, some are pathogenic, with the number of species estimated as fewer than that are seen to cause infectious diseases in humans.
. Pathogenic Gram-Negative Cocci and Bacilli Chapter 20 •Largest group of human pathogens –Due in part to the presence of lipid A in the •Capsules = pathogenic •oxidase positive •Fragile – strict parasites •2 species are pathogenic to humans –The gonococcus, N.
gonorrhoeae. Pathogenic Gram-Negative Cocci: Neisseria •Oxidase positive •Distinguishes from many other Gram-negative pathogens •Pathogenic strains have fimbriae, a polysaccharide capsule, and a cell wall containing lipid A •Two species are pathogenic to humans.
The Gram-positive cocci are the leading pathogens of humans. It is estimated that they produce at least a third of all the bacterial infections of humans, including strep throat, pneumonia, otitis media, meningitis, food poisoning, various skin diseases and severe types of septic shock.