Molecular characterization of mutation in the parC and gyrB genes that confer fluoroquinolone resistance in Streptococcus pneumonia isolates

Abstract

Resistance of Streptococcus pneumoniae to multiple antibacterial agents, including β-lactams, macrolides, tetracyclines, and co-trimoxazole, has emerged worldwide in the 1980s and 1990s and has emphasized the need for new therapeutic alternatives, such as newer fluoroquinolones. Older fluoroquinolones, such as ciprofloxacin and ofloxacin, have been widely used in the last 2 decades, but their activity against gram-positive pathogens is limited. Newer fluoroquinolones, such as levofloxacin, gatifloxacin, moxifloxacin, and gemifloxacin, have enhanced activity against most respiratory pathogens, and some are being more widely used to treat respiratory tract infections. Therefore, the emergence of fluoroquinolone-resistant S. pneumoniae strains, although worldwide prevalence is low, is a concern to clinicians who manage respiratory tract infections. Aim of the work: The aim of this study was to determine the prevalence of fluoroquinolone resistance Streptococcus pneumoniae (FQRSP) and to examine the genetic relatedness of pneumococcal isolates with parC and gyrB genes mutations in different specimens. Patients and Methods: In this study, Biometra Thermal Cyclar-T Gradient Software PCR system version 4 together with DNASIS 2.6 Sequence Analysis Programs were used to investigate the presence of mutations at quinolone resistance-determining regions of topoisomerase IV and DNA gyrase on 78 S. pneumoniae strains, Among 78 isolates 37 (47.4%) of S. pneumonia isolates were Fluroquinolones susceptible, 12 (15.4%) were with variable susceptibility and 29 (37.2%) were Fluroquinolones resistant. Results: Our study illustrate the role of mutation in the parC & gyrB genes and the effect of mutations in the both genes in fluoroquinolone resistance among S. pneumoniae isolates. Conclusion: Results indicated that there is a significant correlation between quinolone resistance development and mutations in the parC gene and in less significance in the gyrB genes .