Publications
| Emergence of Erythromycin-Resistance (Ery-R) in Invasive Group A Streptococci (IGAS) from Ontario, Canada: (1993-2003) |
Authors: S. J. DREWS, S. M. POUTANEN, A. J. MCGEER, T. MAZZULLI, R. LOVINSKY, J. POWIS, K. GREEN, Y. RZAYEV, S. PONG-PORTER, D. E. LOW, Ontario Invasive Gas Study Group;
Toronto Med. Lab. and Mount Sinai Hosp., Toronto, Canada.
Background: The purpose of this study was to determine trends in Ery-R in IGAS in Ontario between 1993 and 2003.
Method: 3578 IGAS were tested by antibiotic disk diffusion per NCCLS guidelines. Ery and clindamycin (Clinda) double-disk diffusion predicted R mechanisms: inducible (i) and constitutive (c) MLSB phenotypes (Ery-R & Clinda-R) due to target site alteration and M phenotype (Ery-R & Cl-S) due to efflux. M and T serotyping was completed. National prescription (Rx) rates (IMS HEALTH, Canada) were used to estimate Ery, clarithromycin (Clari) and azithromycin (Azi) Rx.
Results: Between 1993 and 2003, Ery-R increased with stabilization from 1998 onward (p<0.0001) (See Figure). From all years combined, Ery-R phenotypes were: M (68%), iMLSB (15%) and cMLSB (17%) (p=0.003). Associations exist for Ery-R vs Clari Rx (r= 0.8, p=0.01), Ery-R vs Azi Rx (r=0.7, p=0.02) and Ery-R vs Ery Rx (r=-0.8, p=0.007). Regression curve analysis indicates that the relationship between Clari-Rx and Ery-R is stronger than that of Azi-Rx vs Ery-R (p=0.03). The dominant M and T serotypes among Ery-R isolates were 1 and 4.
Conclusions: Increased Ery-R correlates with increased Azi and Clari Rx and decreased Ery Rx. Ery-R most strongly correlated with Clari Rx.
Presented At:
45th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy, Washington, DC, 12/16/2005.
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©Copyright
1999 Microbiology Department, Mount Sinai Hospital, Toronto, ON, Canada.
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