Brain abscess

Microbiology

• Direct spread
  • Nose/sinuses: Streptococcus species (especially S. milleri), Haemophilus species, Bacteroides species, Fusobacterium species
  • Teeth: Streptococcus species, Bacteroides species, Prevotella species, Fusobacterium species, Haemophilus species
  • Ears: Enterobacteriaceae, Streptococcus species, Pseudomonas aeruginosa, Bacteroides species
  • Penetrating head trauma: Staphylococcus aureus, Enterobacter species, Clostridium species
  • Neurosurgery: Staphylococcus species, Streptococcus species, Pseudomonas aeruginosa, Enterobacter species
• Hematogenous spread
  • Lungs: Streptococcus species, Fusobacterium species, Actinomyces species
  • Urinary tract: Pseudomonas aeruginosa, Enterobacter species
  • Endocarditis: Viridans group streptococci, Staphylococcus aureus
  • Congenital cardiac malformations (especially right-to-left shunts): Streptococcus species
• Immunocompromised patient
  • HIV: Toxoplasma gondii, Nocardia species, non-tuberculous mycobacteria, Listeria monocytogenes, Cryptococcus neoformans
  • Neutropenia: Gram-negative bacilli, Aspergillus species, mucormycosis, Candida species, Scedosporium species
  • Transplantation: Aspergillus species, Candida species, mucormycosis, Scedosporium species, Enterobacteriaceae, Nocardia species, Toxoplasma gondii, and Mycobacterium tuberculosis
• Plus anaerobes, which are common

Further Reading

• Brain Abscesses. NEJM. 2015;371:447-456. doi: 10.1056/NEJMra1301635