Common Organisms by Patient Population in Bacterial Meningitis

Updated: Mar 15, 2019
Author: Shingo Chihara, MD; Chief Editor: Michael Stuart Bronze, MD 

Bacterial Pathogens and Risk/Predisposing Factors

Table. Bacterial Pathogens and Risk or Predisposing Factors [1, 2, 3, 4, 5] (Open Table in a new window)

Risk and/or Predisposing Factor

Bacterial Pathogen

Age 18-50 y

Streptococcus pneumoniae, Neisseria meningitidis

Age >50 y

S pneumoniae, N meningitidis, Listeria monocytogenes, aerobic gram-negative bacilli

Immunocompromised state

S pneumoniae, N meningitidis, L monocytogenes, aerobic gram-negative bacilli

Postneurosurgery

Aerobic gram-negative bacilli (including Pseudomonas aeruginosa), Staphylococcus aureus, coagulase-negative staphylococci (especially Staphylococcus epidermidis)

Basilar skull fracture

S pneumoniae, Haemophilus influenzae, group A β-hemolytic streptococci

Cerebrospinal fluid shunt

Coagulase-negative staphylococci (especially S epidermidis), S aureus, aerobic gram-negative bacilli, Propionibacterium acnes