The detection of penicillin insensitivity in Neisseria meningitidis by polymerase chain reaction.

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.