Recommendations for specific antimicrobial therapy of bacterial meningitis in adults based on isolated pathogen and susceptibility testing*

Microorganism, susceptibility	Standard therapy	Alternative therapies^¶
Streptococcus pneumoniae
Penicillin MIC
≤0.06 mcg/mL	Penicillin G or ampicillin	Third-generation cephalosporin^Δ, chloramphenicol
≥0.12 mcg/mL
Third-generation cephalosporin^Δ MIC <1 mcg/mL	Third-generation cephalosporin^Δ	Cefepime, meropenem
Third-generation cephalosporin^Δ MIC ≥1 mcg/mL	Vancomycin plus a third-generation cephalosporin^Δ^◊	Fluoroquinolone^§
Neisseria meningitidis
Penicillin MIC
<0.1 mcg/mL	Penicillin G or ampicillin	Third-generation cephalosporin^Δ, chloramphenicol
0.1 to 1.0 mcg/mL	Third-generation cephalosporin^Δ	Fluoroquinolone, meropenem, chloramphenicol
Listeria monocytogenes	Ampicillin^¥ or penicillin G^¥	Trimethoprim-sulfamethoxazole
Streptococcus agalactiae (group B Streptococcus)	Ampicillin or penicillin G	Third-generation cephalosporin^Δ
Escherichia coli and other Enterobacteriaceae^‡	Third-generation cephalosporin^Δ	Aztreonam, fluoroquinolone, meropenem, trimethoprim-sulfamethoxazole, ampicillin
Pseudomonas aeruginosa^‡	Cefepime or ceftazidime	Aztreonam, ciprofloxacin, meropenem
Acinetobacter baumannii	Meropenem	Colistin (usually formulated as colistimethate sodium)^† or polymyxin B^†
Haemophilus influenzae
Beta-lactamase negative	Ampicillin	Third-generation cephalosporin^Δ, cefepime, fluoroquinolone, aztreonam, chloramphenicol
Beta-lactamase positive	Third-generation cephalosporin^Δ	Cefepime, fluoroquinolone, aztreonam, chloramphenicol
Staphylococcus aureus
Methicillin susceptible	Nafcillin or oxacillin	Vancomycin, meropenem, linezolid, daptomycin
Methicillin resistant	Vancomycin**	Trimethoprim-sulfamethoxazole, linezolid, daptomycin
Staphylococcus epidermidis	Vancomycin**	Linezolid
Enterococcus species
Ampicillin susceptible	Ampicillin plus gentamicin	...
Ampicillin resistant	Vancomycin plus gentamicin	...
Ampicillin and vancomycin resistant	Linezolid	...

MIC: minimum inhibitory concentration.
* For recommended dosages, refer to the UpToDate table on the recommended intravenous doses of antimicrobial therapy for adults with bacterial meningitis.
¶ There may not be clinical data to support all recommendations for alternative antibiotics in patients with bacterial meningitis, but specific agents are recommended based on cerebrospinal fluid (CSF) penetration in experimental animal models and in vitro activity against the offending organism.
Δ Ceftriaxone or cefotaxime.
◊ Consider addition of rifampin if the MIC of ceftriaxone is >2 mcg/mL.
§ Moxifloxacin is recommended given its excellent CSF penetration and in vitro activity against Streptococcus pneumoniae, although there are no clinical data available. If used, many authorities would combine moxifloxacin with vancomycin or a third-generation cephalosporin (cefotaxime or ceftriaxone).
¥ Addition of an aminoglycoside should be considered.
‡ Choice of a specific antimicrobial regimen must be guided by in vitro susceptibility test results.
† Should be administered not only by the intravenous route but also by the intraventricular or intrathecal route.
** Consider addition of rifampin.

Reference:

van de Beek D, Brouwer MC, Thwaites GE, Tunkel AR. Advances in the treatment of bacterial meningitis. Lancet 2012; 380:1693.

Modified with permission from: Tunkel AR, Hartman BJ, Kaplan SL, et al. Practice guidelines for the management of bacterial meningitis. Clin Infect Dis 2004; 39:1267. Copyright © 2004 University of Chicago Press.

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