Background and Aim:  Increased resistance to the macrolides is probably due to excessive and inappropriate use of this type of antibiotics.  The  purpose  of this study was to investigate  macrolide resistance in  group A Streptococci  strains  isolated  from  clinical  samples carrying mef  gene and comparison of the  phenotype and genotype of the mef gene carriers and  prevalence of bacteria in  the  study   population.

Material and methods: Forty Beta-hemolytic streptococci pyogenes group A isolates obtained from 825 various clinical specimens by using disk agar diffusion (DAD) were studied for the presence of mefA and mefE genes by polymerase chain reaction (PCR). Statistical analysis was performed by means of SPSS and Microsoft Office Excel softwares.

Results: Prevalence of group  A  streptococcus  was   4.84 %  and also we found a macrolide resistance of  40% among  isolates in  the  study   population.  By using  D-test, the  prevalence  rates of phenotypes of GAS resistant  to  erythromycin among  8 isolates were  50% (4cases) for M-phenotyp,37.5% (3 cases) for cMLS- phenotype  and 12.5% (1 case) for iMLSB -phenotype 1. Among 16 isolates resistant to macrolides, 8 (50%) had  mefA,  one (6.25%) had mefE  and  7  isolates (43.75%), didn^,t have  mefA / E genes. 

Conclusion: In the present study M- phenotype had the highest frequency among GAS isolates resistant to erythromycin. Also, PCR can be used as a confirmatory routine test for interpretation of the results of anti-biogram and D-tests.

Keywords: Beta-hemolytic streptococci group A, Macrolides, MLSB, D-TEST, Gene mef.

Received: Jul 27, 2015      Accepted: Jun 21, 2016