Frequency of oqxA and oqxB Plasmid-Mediated Quinolone Resistance Genes in Escherichia Coli Isolated from Urine of Inpatients with Urinary Tract Infections in Yazd City, Iran

Increasing in resistance among Escherichia coli causing urinary tract infection led to increased concern in the world. Quinolones are widely used in the treatment of urinary tract infections and a few studies have been done about plasmid-mediated quinolone resistance determinants. The aim of this study was to determine the frequency of oqxA and oqxB plasmid-mediated quinolone resistance genes, which encodes efflux pumps, among Escherichia coli isolated from urine of hospitalized patients with urinary tract infection in Yazd City, Iran.
In this descriptive–analytical study, 94 Escherichia coli strains were isolated from urine specimens of inpatients with urinary tract infections in Yazd City, at first 6 months of 2014. The susceptibility testing for quinolones were performed using the disk diffusion method according to protocols of Clinical and Laboratory Standards Institute (CLSI-2013). Polymerase chain reaction (PCR) method and specific primers were used for detection of oqxA and oqxB genes. The results were analyzed using SPSS software.
Findings: Among 94 Escherichia coli isolates, the lowest and highest quinolone-resistance was observed for norfloxacin (51.0%) and nalidixic acid (73.4%), respectively. In this study, oqxA and oqxB genes were present in 4 (4.2%) and 3 (3.2%) Escherichia coli isolates, respectively.
According to the results, resistance to quinolones is higher than some other studies. The low frequency of oqxA and oqxB in this study was similar to other studies. It is recommended that antibiotic susceptibility test must be performed routinely before initiating treatment of urinary tract infections and studies about the plasmid-mediated quinolone resistance determinants should be done regularly.