NICHOL KA, SMITH HJ, HOBAN DJ, ZHANEL GG; Interscience Conference on Antimicrobial Agents and Chemotherapy (41st : 2001 : Chicago, Ill.).

Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 2001 Dec 16-19; 41: abstract no. C2-701.

Health Sciences Centre, Winnipeg, MB, Canada

BACKGROUND: In recent years, an increased proportion of SP isolates have demonstrated resistance to respiratory FQs. Few studies, however, have examined the molecular epidemiology of SP with reduced FQ susceptibility. The purpose of this study was to assess the genetic relatedness among FQ-resistant (Ciprofloxacin [Cipro] MIC >/= 4 microg/ml) clinical isolates of SP from major population centres within Canada. METHODS: All Cipro-nonsusceptible SP (26 isolates) and a random cohort of 63 susceptible SP were selected from among 1652 isolates collected between 1999 and 2000 as part of an ongoing national surveillance study. MICs to Cipro were determined by broth microdilution as specified by the NCCLS (2000). Isolates were genotyped by SmaI pulsed-field gel electrophoresis (PFGE). Serotyping was performed by the Quellung reaction. RESULTS: Cipro MICs were interpreted as /= 16 microg/ml (high-level resistance, HLR). 14 SP isolates showed LLR while 12 isolates showed HLR. 63 isolates were Cipro-susceptible (Cipro-S). PFGE revealed 10 unique genotypes amongst the 12 HLR isolates and exclusive heterogeneity amongst LLR SP. 54/63 Cipro-S isolates exhibited unique PFGE patterns. Dendrogram analysis revealed 10 epidemiologic clusters (>/= 90% genetic relatedness), the majority (5/10) of which consisted entirely of Cipro-S SP. Only 2 clusters of HLR isolates were observed. Some overlap was observed among PFGE types between HLR and LLR SP (1 cluster) and between LLR and Cipro-S SP (2 clusters). Cophenetic correlations amongst HLR, LLR and Cipro-S SP were 77.5, 71.3 and 76.6%, respectively. CONCLUSION: Molecular typing demonstrated considerable genetic variability amongst FQ-resistant SP, with no specific PFGE profile correlating with Cipro non-susceptibility. This suggests that the emergence of Cipro-resistant SP in Canada is currently not attributable to clonal dissemination.

Publication Types:

• Meeting Abstracts

Keywords:

• Canada
• Ciprofloxacin
• Electrophoresis, Gel, Pulsed-Field
• Fluoroquinolones
• Microbial Sensitivity Tests
• Serotyping
• Streptococcus pneumoniae

Other ID:

• GWAIDS0030648

UI: 102270285

From Meeting Abstracts