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The detection of penicillin insensitivity in Neisseria meningitidis by polymerase chain reaction
A F Maggs1, J M Logan, P E Carter
1Department of Medical Microbiology, University of Dundee Medical School, Ninewells Hospital, UK.
Abstract:
Strains of penicillin-sensitive and -insensitive Neisseria meningitidis were examined using a range of polymerase chain reaction (PCR) primers directed at the meningococcal penicillin-binding protein 2 gene. DNA from isolates whose penicillin MIC was <0.2 mg/L yielded a product of the expected size with all the primers, but many amplification patterns were seen with DNA from isolates whose MIC was above this level. All strains whose MIC was >0.25 mg/L failed to produce a product of the expected size with at least one of the primers used. The changes seen in penicillin-insensitive strains were consistent with horizontal gene transfer from Neisseria flavescens in some isolates, although the source for others remains unknown. PCR-based methods for the detection of antibiotic resistance are becoming increasingly important with the expanding use of molecular techniques for bacteriological diagnosis.
Insights
Penicillin resistance in Neisseria meningitidis is linked to changes in the penicillin-binding protein 2 gene, detected via polymerase chain reaction (PCR). These genetic alterations, possibly from horizontal gene transfer, impact antibiotic effectiveness.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Neisseria meningitidis is a significant human pathogen.
- Antibiotic resistance, particularly to penicillin, is a growing concern in bacterial infections.
- Understanding the genetic basis of penicillin resistance is crucial for effective treatment.
Purpose of the Study:
- To investigate the genetic alterations in the penicillin-binding protein 2 gene associated with penicillin resistance in Neisseria meningitidis.
- To evaluate the utility of polymerase chain reaction (PCR) for detecting these genetic changes.
Main Methods:
- Analysis of penicillin-sensitive and -insensitive Neisseria meningitidis strains.
- Use of various PCR primers targeting the meningococcal penicillin-binding protein 2 gene.
- Determination of minimum inhibitory concentrations (MICs) for penicillin.
Main Results:
- Penicillin-sensitive strains (MIC <0.2 mg/L) showed consistent PCR amplification patterns.
- Penicillin-insensitive strains (MIC >0.25 mg/L) exhibited altered PCR amplification, with some failing to produce expected product sizes.
- Observed genetic changes in resistant strains suggest horizontal gene transfer, potentially from Neisseria flavescens.
Conclusions:
- PCR is a valuable tool for detecting genetic changes associated with penicillin resistance in Neisseria meningitidis.
- Horizontal gene transfer appears to play a role in the emergence of penicillin resistance.
- Further research is needed to identify the sources of gene transfer in all resistant isolates.