Publications
| Ontario Group A Streptococcal Study Group. Reduced ketolide susceptibility in clinical group A streptococci (GAS) in Ontario, Canada. |
Authors: R. Lovinsky, D.E. Low, J.C.S. deAzavedo, L. Trpeski, M. Lovgren, G. Tyrrell, B.M. Willey, S. Pong-Porter, A. McGeer.
Background: Ketolide resistant (R) GAS has not been reported in North America but has been described in Europe. We evaluated the activity of telithromycin (TEL) and ABT-773 (ABT) against clinically significant macrolide-R GASin Ontario.
Method: Population based surveillance for GAS disease has been performed in Ontario (pop. 11M) since 1992. 95/2226 isolates were found to be erythromyin (E)-R. MIC to E, clindamycin (C), TEL and ABT were determined by NCCLS broth microdilution.
Results: 4/95 (4.2%) E-R GAS were TEL-R (>1µg/ml); 10 had intermediate susceptibility (1mg/ml). 2/95 GAS (2.1%) had ABT MIC of 2 and 8 mg/ml; both were TEL-R. All 4 TEL-R had E MIC >64µg/ml and 3/4 were C-R (MIC >64µg/ml). The 10 TEL intermediate strains had E MIC >l8 µg/ml and were all susceptible to C (MEF phenotype). The first TEL intermediate GAS was found in 1992; the first TEL-R, in 1997. GAS with reduced susceptibility to TEL included 10 M types.
Conclusions: Although ketolides are active against most E-R GAS in our data base, the combination of increased macrolide use and the introduction of ketolides may result in future clinically significant rates of resistance to these agents.
Presented At:
41st Annual Interscience Conference on Antimicrobial Agents and Chemotherapy, Chicago, Illinois, 12/16/2001.
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©Copyright
1999 Microbiology Department, Mount Sinai Hospital, Toronto, ON, Canada.
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