Enterobacter meningitis: organism susceptibilities, antimicrobial therapy and related outcomes

Meningitis due to Enterobacter species is an uncommon infection in adults; however, when present, treatment is frequently complicated by resistance of many Enterobacter isolates to third-generation cephalosporins and poor central nervous system penetration of other antibiotics. The aim of this study was to retrospectively review cases of meningitis caused by Enterobacter species at our institution, to better characterize patient factors, pathogen characteristics, and treatment options for this infection.

We reviewed all cases of Enterobacter meningitis in a 12-year period at a tertiary care center. Data collected included patient demographics, antibiotic sensitivities of Enterobacter isolates, antimicrobial therapy, and patient outcomes.

Nineteen cases were identified, primarily in patients with neurotrauma and in neurosurgical patients. Enterobacter cloacae was the most frequent Enterobacter species isolated followed by Enterobacter aerogenes and Enterobacter agglomerans (50%, 34%, and 16% of cultures, respectively). Overall, clinical cure/improvement was achieved in 47% of patients, and the mortality rate was 21%. Antibiotic treatment varied substantially and included third-generation cephalosporins, intravenous and intrathecal aminoglycosides, trimethoprim-sulfamethoxazole (TMP-SMX), piperacillin, ciprofloxacin, and other miscellaneous antibiotics. Treatment with TMP-SMX was associated with a high rate of clinical cure/improvement, whereas third-generation cephalosporins were less efficacious.

Enterobacter meningitis is an infrequent complication of neurological insult. Treatment is often complicated by resistance of Enterobacter species to third-generation cephalosporins. Our results indicate that while third-generation cephalosporins are not the most appropriate choice of agents to treat Enterobacter meningitis, TMP-SMX may yield satisfactory results.