Extremely High Prevalence of Erythromycin Resistance of Group A Beta Hemolytic Streptococci in Mash'had (Iran)

Erythromycin has been the classic drug of choice for Streptococcal pharyngitis in case of allergy to penicillin. To determine the resistance rate of Group A beta hemolytic Streptococci (GABHS) to erythromycin in Mashhad (population 2,500,000), we performed a biphasic research, composed of two retrospective (April 1998- March 1999 and April 2003-March 2005) and a prospective studies. In the first part, we collected GABHS positive cultures and their (disk diffusion) antibiograms from three medical diagnosis laboratories in Mashhad. In the second phase, in April 2005, throat cultures were taken from 204 elementary, high school and college students; antibiograms were done by both disk diffusion and E-test. In the retrospective study, during 1998-1999, thirty-seven of 62 (59.67%) GABHS isolated samples and during 2003-2005, thirty-six of 44 (81.87%) GABHS isolates were resistant to erythromycin. The mean age of the 2003-2005 group was 25.5 years. The resistance rate in children less than 10 years old was 71.42% and in the older ones 88.23% (P=0.07).