Molecular Investigation of Quinolone Resistance of Quinolone Resistance-Determining Region in Streptococcus pneumoniaeStrains Isolated from Iran Using Polymerase Chain ReactioneRestriction Fragment Length Polymorphism Method

Objectives:The resistance ofStreptococcus pneumoniaeto the recently available antibiotic treatment has been a growing problem. The aim of the study was to determine the quinolone-resistant strains and detect the presence of mutations in the quinolone resistance-determining regions of thegyrA,parE, andparCgenes. Methods:In this study, for the first time in Iran, the polymerase chain reactione restriction fragment length polymorphism (PCR-RFLP) method was used to investigate the presence of mutations at quinolone resistance-determining regions of topoisomerase IV and DNA gyrase on 82S. pneumoniaestrains, among them 45 clinical samples were from patients and 37 from healthy carriers (control group). Results:In clinical samples, 34 (75.56%) strains contained mutations in the parC gene, 31 (68.89%) carried mutations in thegyrAgene, and 14 (31.11%) hadparE gene mutations. Antibiotic susceptibility test was performed using the CLSI (Clinical and Laboratory Standards Institute) criteria on three different generations of quinolone family, with nalidixic acid (82.22%) showing the highest resistance and levofloxacin (42.22%) the least resistance. Conclusion:Results indicated that there is a significant correlation between quinolone resistance development and mutations in theparEgene as well as in the parCandgyrAgenes.

gyrA, parC, parE, polymerase chain reactionerestriction fragment length polymorphism, quinolones, Streptococcus pneumoniae