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Acute bacterial meningitis in adults. A 12-year review
1Division of Infectious Diseases, Department of Medicine, University of Alberta, Edmonton, Canada.
Abstract:
One hundred three episodes of acute bacterial meningitis in adults hospitalized in Edmonton's 2 largest hospitals from 1985 to 1996 were reviewed. Cases complicating neurosurgery were excluded. Most cases were community-acquired (87%). Twenty-three cases remained culture-negative, and there was no statistical relation between culture negativity and antibiotic pretreatment. Streptococcus pneumoniae was the predominant pathogen (52.5%), but Listeria monocytogenes was the second most common isolate, accounting for 12.5% of culture-positive cases. Compared to non-listerial meningitis, those with listeriosis were more likely to have negative cerebrospinal fluid (CSF) Gram stains (p = 0.07), CSF leukocyte counts < 1,000 cells/mm3 (p < 0.003), and normal CSF glucose (p = 0.006). Bacterial antigen detection was found to be of low sensitivity: 33% in all patients, but only 9% in cases with negative CSF Gram stains. The overall mortality was 18%, with 15 deaths directly attributable to acute meningitis; the case-fatality rates for S. pneumoniae and L. monocytogenes were 24% and 40%, respectively. Mortality was significantly higher among those with seizures (34% versus 7%, respectively; p < 0.001; OR = 17.6). Despite the urgency of acute bacterial meningitis, there were considerable delays in the institution of empiric antibiotics; mortality rates were slightly higher in those who experienced such a delay (16% versus 7% respectively; p = 0.18).
Insights
Acute bacterial meningitis in adults is often community-acquired, with Streptococcus pneumoniae and Listeria monocytogenes as key pathogens. High mortality rates were observed, particularly with L. monocytogenes and seizures, despite delayed antibiotic treatment.
Area of Science:
- Infectious Diseases
- Neurology
- Critical Care Medicine
Background:
- Acute bacterial meningitis remains a significant cause of morbidity and mortality in adults.
- Understanding the epidemiology and clinical characteristics of bacterial meningitis is crucial for timely diagnosis and treatment.
- Community-acquired meningitis constitutes the majority of cases, highlighting the importance of early recognition outside healthcare settings.
Purpose of the Study:
- To review and analyze episodes of acute bacterial meningitis in adults admitted to major hospitals in Edmonton.
- To identify predominant pathogens, clinical features, diagnostic challenges, and outcomes, including mortality rates.
- To investigate the impact of specific pathogens like Listeria monocytogenes and clinical factors such as seizures on patient prognosis.
Main Methods:
- Retrospective review of 103 adult acute bacterial meningitis cases hospitalized between 1985 and 1996.
- Exclusion of cases secondary to neurosurgery.
- Analysis of causative pathogens (culture-positive and negative), cerebrospinal fluid (CSF) findings, diagnostic test sensitivity, and patient outcomes (mortality, seizures, treatment delays).
Main Results:
- Streptococcus pneumoniae (52.5%) and Listeria monocytogenes (12.5%) were the most common pathogens in culture-positive cases.
- Listeriosis cases showed trends towards negative CSF Gram stains, lower CSF leukocyte counts, and normal CSF glucose compared to other bacterial meningitis.
- Overall mortality was 18%, with higher case-fatality rates for L. monocytogenes (40%) and S. pneumoniae (24%). Seizures were associated with significantly higher mortality (34% vs. 7%).
Conclusions:
- Acute bacterial meningitis in adults is predominantly community-acquired, with S. pneumoniae and L. monocytogenes being significant etiological agents.
- Listeria monocytogenes infections present with distinct CSF characteristics and carry a high mortality risk.
- Delays in empiric antibiotic administration and the occurrence of seizures are associated with increased mortality, underscoring the need for prompt diagnosis and management.