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Prevalence and Mechanisms of Macrolide Resistance in Clinical Isolates of Group A Streptococci from Ontario, Canada

1999; American Society for Microbiology; Volume: 43; Issue: 9 Linguagem: Inglês

10.1128/aac.43.9.2144

1098-6596

Joyce C. S. de Azavedo, Rani Yeung, Darrin J. Bast, Carla Duncan, S. B. Borgia, Donald E. Low,

Infective Endocarditis Diagnosis and Management

ABSTRACT A total of 3,205 group A streptoccal isolates were collected in 1997 through a private laboratory which serves community physicians in southern Ontario and which represents a population base of 6 million people. Nonsusceptibility to erythromycin was detected for 67 (2.1%) isolates both by disk diffusion and by broth microdilution. Of these, 47 (70%) were susceptible to clindamycin and were found by PCR to possess the mef gene. Of the other 20 strains, 18 and 2 showed inducible and constitutive resistance, respectively, to clindamycin. Nineteen of these strains were shown by PCR to possess the ermTR gene, and a single constitutively resistant strain harbored an ermB gene. Sixteen (24%) erythromycin-resistant strains were also resistant to tetracycline. All were susceptible to penicillin and chloramphenicol.