Antibiotic treatment and mortality in patients with Listeria monocytogenes meningitis or bacteraemia

OBJECTIVES: Invasive Listeria monocytogenes infections carry a high mortality despite antibiotic treatment. The rareness of the infection makes it difficult to improve antibiotic treatment through randomised clinical trials. This observational study investigated clinical features and outcome of invasive L. monocytogenes infections including the efficacy of empiric and definitive antibiotic therapies.

METHODS: Demographic, clinical and biochemical findings, antibiotic treatment, and 30-days mortality for all episodes of L. monocytogenes bacteraemia and/or meningitis were collected by retrospective medical record review in North Denmark Region and the Capital Region of Denmark (17 hospitals) from 1997 through 2012. Risk factors for 30-day all-cause mortality were assessed by logistic regression.

RESULTS: The study comprised 229 patients (median age: 71 years), 172 patients had bacteraemia, 24 patients had meningitis and 33 patients had both. Significant risk factors for 30-day mortality were septic shock (OR: 3.0, (95% CI 1.4-6.4)), altered mental state (OR: 3.6 (1.7-7.6)), and inadequate empiric antibiotic therapy (OR: 3.8 (1.8-8.1)). Cephalosporins accounted for 90% of inadequately treated cases. Adequate definitive antibiotic treatment was administered to 195 patients who survived the early period (benzylpenicillin 72, aminopenicillin 84, meropenem 28, sulfamethoxazole/trimethoprim 6, and piperacillin/tazobactam 5). Definitive antibiotic treatment with benzylpenicillin or aminopenicillin resulted in a lower 30-days mortality in an adjusted analysis compared to meropenem (OR: 0.3 (0.1-0.8)).

CONCLUSION: Inadequate empiric antibiotic therapy and definitive therapy with meropenem were both associated with significantly higher 30-day mortality.