Spontaneous gram-negative meningitis

Background

Microbiology

• Most commonly caused by Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter
• Also Citrobacter, Serratia marcescens, Enterobacter, and Proteus mirabilis
• Typically excludes usual causes of meningitis such as Haemophilus or Neisseria

Risk Factors

• Diabetes mellitus
• Cirrhosis
• End-stage renal disease
• Substance abuse, including alcohol use disorder
• Cancer

Clinical Presentation

• As per other forms of bacterial meningitis

Management

• CNS dosed antibiotics to complete 21 days is typically sufficient

Organism	First-line	Second-line	Duration
E. coli and other Enterobacteriaceae	third-generation cephalosporin	ampicillin, meropenem, aztreonam, TMP-SMX, or ciprofloxacin	21 days
Pseudomonas aeruginosa	cefipime or ceftazidime	meropenem, aztreonam, or ciprofloxacin
ESBL Gram-negative bacillus	meropenem	cefepime or a fluoroquinolone