Molecular epidemiology survey of penicillin-susceptible and -resistant Streptococcus pneumoniae recovered from patients with meningitis in France

The genetic diversity of Streptococcus pneumoniae isolates (n = 291) recove red from cerebrospinal fluid of patients with meningitis in France was inve stigated by restriction fragment length polymorphism analysis of the riboso mal RNA gene regions and of the pbp2b and 2x genes. Statistical analysis of the data by factorial analysis of correspondence established the following : penicillin-susceptible isolates had a high level of genetic diversity, es pecially those belonging to serogroups frequently associated with carriage; capsular serotype switches could occur among penicillin-susceptible and -r esistant isolates; and the mechanisms of acquired penicillin resistance wer e clearly distinct in isolates with penicillin minimum inhibitory concentra tion (MIC) values <1 mg/L and isolates with penicillin MIC values greater t han or equal to 1 mg/L. Thus, an increase in the penicillin MIC for a given strain, from intermediate to high-level resistance would be a rare event.