Multi-drug resistance and molecular pattern of erythromycin and penicillin resistance genes in Streptococcus pneumoniae

resistant strains to erythromycin (56%), penicillin (40%), ampicillin (56%), cefotaxime (50%), tetracycline (10%), trimethoprim-sulfamethoxazole (48%), nalidixic acid (16%), clarithromycin (48%), azithromycin (44%) and levofloxacin (4%). All strains were susceptible to chloramphenicol, amikacin, streptomycin and gentamicin. Gene analysis showed that 29 strains (58%) had mef(A) gene, and 24 strains (48%) had the erm(B) gene. Out of all the penicillin resistance and intermediate strains, 6 (20%) and 1 (3.33%) strains harbor mutations in pbp1a and pbp2x genes, respectively, but pbp2b was not identified in any sample. Resistance to penicillin, trimethoprim-sulfamethoxazole, clarithromycin and azithromycin in S. pneumoniae is a serious problem in this area and the local pattern of resistance/susceptibility must be considered for therapeutic regimens. The mef(A) gene was a predominant mechanism of macrolide resistance in this area. With regards to low frequency of pbps resistance genes, monitoring of other kinds of mechanisms is recommended.