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Detection and serogroup determination of Neisseria meningitidis in CSF by polymerase chain reaction (PCR)
R J Porritt1, J L Mercer, R Munro
1Department of Microbiology & Infectious Diseases, South Western Area Pathology Service, Sydney, Australia.
Abstract:
A PCR protocol for the detection and serogroup determination of Neisseria meningitidis in CSF from 85 cases of suspected meningitis was evaluated. Screening assays for both IS1106 and the ctrA gene were used to detect meningococcal DNA, and a further two assays using the siaD gene were performed to determine the serogroup. PCR results were compared with results of bacteriological culture and discrepant results resolved by analysis of clinical data and further laboratory test results. The resolved sensitivity and specificity of the PCR screening assay were 89 and 100%, and those of bacteriological culture were 37 and 100%, respectively. The siaD B/C PCR assay was able to determine a serogroup in 85% of cases positive by the PCR screening assay compared with 50% of cases where a serogroup was determined by traditional methods. PCR is a useful tool for diagnosis of meningococcal meningitis when Gram stain and culture tests are negative, a situation that may arise when antibiotic treatment has commenced prior to lumbar puncture.
Insights
Polymerase chain reaction (PCR) offers a sensitive method for detecting Neisseria meningitidis DNA in cerebrospinal fluid (CSF). This molecular technique aids in diagnosing meningococcal meningitis, especially when traditional tests are negative.
Area of Science:
- Microbiology
- Molecular Diagnostics
- Infectious Diseases
Background:
- Neisseria meningitidis is a primary cause of bacterial meningitis.
- Early and accurate diagnosis is crucial for effective treatment and patient outcomes.
- Conventional methods like Gram stain and culture may be negative, particularly after antibiotic treatment.
Purpose of the Study:
- To evaluate a polymerase chain reaction (PCR) protocol for detecting Neisseria meningitidis DNA in cerebrospinal fluid (CSF).
- To assess the capability of PCR for serogroup determination of Neisseria meningitidis.
- To compare the diagnostic performance of PCR with traditional bacteriological culture methods.
Main Methods:
- Evaluation of PCR assays targeting IS1106 and ctrA genes for meningococcal DNA detection.
- Utilized siaD gene-based PCR assays for serogroup determination.
- Compared PCR results with bacteriological culture, resolving discrepancies with clinical and further laboratory data.
Main Results:
- The PCR screening assay demonstrated a resolved sensitivity of 89% and specificity of 100%.
- Bacteriological culture showed a resolved sensitivity of 37% and specificity of 100%.
- The siaD B/C PCR assay determined serogroups in 85% of PCR-positive cases, significantly higher than traditional methods (50%).
Conclusions:
- PCR is a valuable diagnostic tool for meningococcal meningitis, especially when Gram stain and culture are negative.
- PCR provides improved sensitivity over culture for detecting Neisseria meningitidis.
- The developed PCR method effectively determines serogroups, aiding in epidemiological surveillance and management.