[Macrolide antibiotic resistance rates and phenotypes of group A beta hemolytic streptococci isolated between the years 1999-2000 and 2001-2002].

Macrolide resistance in group A beta hemolytic streptococci (GABHS) have been reported with increasing frequency from various geographic regions in the world, and for the respective treatment alternatives and epidemiologic studies, macrolide resistance rates and phenotypes have been determined. In this study erythromycin, clarithromycin and azithromycin were tested with disc diffusion method against 560 GABHS, isolated from the throat samples collected between 1999-2002. NCCLS guidelines were followed for the susceptibility tests and MIC values were obtained by E-Test in resistant isolates. For determining the resistance phenotype, erythromycin and clindamycin discs were used. Only one isolate (0.27%) was found intermediately resistant to erythromycin, and clarithromycin, and resistant to azithromycin between May 1999-January 2000, whereas in the period between January 2001-June 2002, one isolate (%0.5) was found susceptible to erythromycin and clarithromycin, but intermediately resistant to azithromycin. In each period three isolates (0.83% and 1.5%, respectively) were found to be resistant to all the tested macrolides. There was no statistically significant difference between the resistance rates in these periods. Three of the resistant isolates had inducible type, and the other five isolates had M phenotype macrolide resistance. Testing for macrolide susceptibilities and screening the resistance phenotypes have crucial importance in case of GABHS infections, since these can be taken into consideration for epidemiological issues as well as a guide for empirical treatment protocols in any geographical setting, as well as in our country.