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Mixed bacterial meningitis
N J Downs1, G R Hodges, S A Taylor
1Medical Service, Veterans Administration Medical Center, Kansas City, Missouri 64128.
Abstract:
Two recent cases of mixed bacterial meningitis at the Kansas City Veterans Administration Medical Center were studied. A review of the literature suggests that 1% of all cases of meningitis are caused by more than one bacterial species. Before 1950 such cases occurred predominantly in children and were caused by combinations of bacteria commonly associated with meningitis. Since 1950 a largely adult population has been affected by mixed bacterial meningitis, with a higher incidence of gram-negative bacillary organisms cultured from the cerebrospinal fluid. Common predisposing factors in this older group of patients include infection at contiguous foci, tumors in close proximity to the central nervous system, or fistulous communications with the central nervous system. Mortality was 26% for cases occurring before 1950 and 63% for those occurring after 1950. Failure to recognize one of the organisms present in the cerebrospinal fluid may result in the initiation of inadequate therapy in as many as 67% of cases. Empiric broad-spectrum antimicrobial therapy is indicated in symptomatic patients predisposed to mixed bacterial meningitis until culture results become available.
Insights
Mixed bacterial meningitis, caused by multiple bacteria, affects adults more often now. Early broad-spectrum antibiotics are crucial for better outcomes in predisposed patients.
Area of Science:
- Neurology
- Infectious Diseases
- Microbiology
Background:
- Meningitis is an inflammation of the membranes surrounding the brain and spinal cord.
- Mixed bacterial meningitis, involving multiple bacterial species, accounts for approximately 1% of all meningitis cases.
Observation:
- Historically, mixed bacterial meningitis predominantly affected children with common bacterial pathogens.
- Since 1950, there has been a shift towards an adult population affected by mixed bacterial meningitis.
- Gram-negative bacillary organisms are increasingly cultured from cerebrospinal fluid in adult cases.
Findings:
- Predisposing factors in adults include contiguous infections, central nervous system tumors, and fistulous communications.
- Mortality rates have significantly increased, from 26% before 1950 to 63% after 1950.
- Failure to identify all causative organisms can lead to inadequate therapy in up to 67% of cases.
Implications:
- Recognizing the changing demographics and causative agents of mixed bacterial meningitis is critical.
- Prompt empiric broad-spectrum antimicrobial therapy is recommended for at-risk patients presenting with symptoms.
- Early and accurate diagnosis and treatment are essential to improve patient outcomes and reduce mortality.