Spontaneous gram-negative bacillary meningitis in adult patients: characteristics and outcome

Virginia Pomar,Pere Coll,Natividad Benito,Mercedes Gurguí,Joaquin López-Contreras,Pere Domingo

doi:10.1186/1471-2334-13-451

Abstract

BackgroundSpontaneous meningitis caused by gram-negative bacilli in adult patients is uncommon and poorly characterized. Our objective is to describe and compare the characteristics and the outcome of adult patients with spontaneous gram-negative bacilli meningitis (GNBM) and spontaneous meningitis due to other pathogens.MethodsProspective single hospital-based observational cohort study conducted between 1982 and 2006 in a university tertiary hospital in Barcelona (Spain). The Main Outcome Measure: In-hospital mortality.ResultsGram-negative bacilli meningitis was diagnosed in 40 (7%) of 544 episodes of spontaneous acute bacterial meningitis. The most common pathogens were Escherichia coli and Pseudomonas species. On admission, characteristics associated with spontaneous gram-negative bacilli meningitis by multivariate modeling were advanced age, history of cancer, nosocomial acquisition of infection, urinary tract infection as distant focus of infection, absence of rash, hypotension, and a high cerebrospinal fluid white-cell count. Nine (23%) episodes were acquired in the hospital and they were most commonly caused by Pseudomonas. The in-hospital mortality rate was 53%. The mortality rate was higher among patients with Gram-negative bacillary meningitis than among those with other bacterial meningitis and their risk of death was twenty times higher than among patients infected with Neisseria meningitidis (odds ratio 20.47; 95% confidence interval 4.03-103.93; p<0.001).ConclusionsGram-negative bacilli cause 9% of spontaneous bacterial meningitis of known etiology in adults. Characteristics associated with GNBM include advanced age, history of cancer, nosocomial acquisition, and urinary tract infection as distant focus of infection. The mortality rate is higher among patients with gram-negative bacillary meningitis than among those with other bacterial meningitides.

Highlights

Spontaneous meningitis caused by gram-negative bacilli in adult patients is uncommon and poorly characterized
Much of the current understanding of gram-negative bacilli meningitis (GNBM) in adults is based on studies that are limited by retrospective design and analysis that combine patients with spontaneous meningitis and meningitis secondary to trauma or neurosurgery [10,11,12,14,15,16]
The diagnosis of meningitis caused by a specific bacterial pathogen was based on compatible clinical findings and one of the following: a positive cerebrospinal fluid (CSF) culture, or a negative CSF culture with a finding of neutrophilic pleocytosis and at least one of the following: a positive CSF antigen test, a positive blood culture, or identification of gram-negative diplococci on Gram’s staining of CSF in patients with a petechial or purpuric rash and a fulminant course [21]

Summary

Introduction

Spontaneous meningitis caused by gram-negative bacilli in adult patients is uncommon and poorly characterized. Our objective is to describe and compare the characteristics and the outcome of adult patients with spontaneous gram-negative bacilli meningitis (GNBM) and spontaneous meningitis due to other pathogens. Spontaneous meningitis caused by gram-negative bacilli (other than Haemophilus influenzae) in adults is an uncommon and poorly characterized disease. Much of the current understanding of GNBM in adults is based on studies that are limited by retrospective design and analysis that combine patients with spontaneous meningitis and meningitis secondary to trauma or neurosurgery [10,11,12,14,15,16]. Most of the scarce literature describing GNBM in adults was published more than a decade ago, and epidemiology and outcomes could have changed in recent years [9,10,12,14,15,16,17,18,19,20]

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