Detection of Mutation in 23S rRNA in Isolates of Streptococcus pyogenes Resistant to Erythromycin

Background: in this study, erythromycin resistance isolates from the students with aged 12-15 yr old were studied and themutations in the 23s rrna were identified by sequencing.methods: throat samples of 327 students with 12-15 years old from 3 schools of tehran were cultured on the selective streptococcus pyogenes medium and 23 strains were primarily selected as s. pyogenes.results: all strains were susceptible to penicillin and bacitracin (0.04u). minimum inhibitory of concentrations (mics) forerythromycin were determined in which 5 strains were found intermediate, 2 strains resistance and the remaining 16 strainssusceptible to erythromycin. mic for the erythromycin-resistance strains, bt3 and bt4, were 8.2 and 12.4 ìg/ml, respectively. pcrwas performed for each six 23s rrna operons and a fragment with 550 bp was sequenced. for two resistance strains, bt3and bt4 there were a mutation in position 2059 (a to g). also another mutation in position 2529 (g to a) was detected in bt3.conclusion: in addition to mutation at the position 2058 other point mutations in different positions of domain v involve inthe resistance to macrolides.