Molecular characterization of penicillin non-susceptible Streptococcus pneumoniae in Christchurch, New Zealand

Objectives: To determine the epidemiological relationship between non-invasive penicillin non-susceptible Streptococcus pneumoniae isolates collected in the Christchurch community between 1997 and 2001. Methods: One hundred and ninety-seven pneumococcal isolates were examined by macrorestriction profile analysis of SmaI-digested genomic DNA separated by PFGE and restriction fragment length polymorphism analysis of penicillin binding protein genes. Results: Four major clonal lineages were identified, the largest and most homogenous containing 95 (48.2%) of the isolates, the bulk of which (93.7%), had identical macrorestriction patterns. Members of this clonal group were multidrug-resistant and exhibited high resistance to third-generation cephalosporins, with MICs ≥8.0 mg/L not uncommon (23.1%). Two of the clonal groups, each containing 24 (12.2%) isolates, appeared indistinguishable from the globally widespread Spain23F-1 and France9V-3 strains, respectively. The fourth (12.7% of isolates) multidrug-resistant clone possessed intermediate penicillin susceptibility (MIC 0.12 mg/L). Conclusions: This study shows that several distinct penicillin-resistant pneumococcal clones are present in the Christchurch community, most of which appear to have been imported into New Zealand.