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 homogeneous 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 > or =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.