Frequency of QnrA and QnrB Ciprofloxacin-resistant Genes in Escherchia Coli Strains Isolated from Urinary Tract Infections in Estahban-Hospitals in Fars Province

Urinary tract infections(UTIs) are regarded as a serious health problem that affects millions of people per year. In fact, Escherchia coli causes about 75%-90% of UTIs. The wide usage of ciprofloxacin has led to an increase in the resistance to this bacterium. Therefore, this study aimed to evaluated frequency of qnrA and qnrB genes in E. coli strains isolated from UTIs at Imam Khomeini hospital in Estahban-Fars province. In this descriptive-analytic study, a total of 224 E. coli strains isolated from the urine samples of the patients suffering from urinary tract infection were collected at Estahban Imam Khomeini Hospital. The susceptibility testing for quinolons were performed by the disk diffusion method according to CLSI 2013 protocols. Moreover, the minimum inhibition concentration(MIC) of ciprfloxacin was determined by the E-test method. Multiplex PCR was carried out in order to evaluate the presence of qnrA and qnrB genes in the Cipro floxacin-resistant isolates applying the specific primers. Moreover, the study data were statistically analyzed by SPSS software (V.16). 224 isolates were obtained via applying MIC, out of which 88 (39.2%) isolates were resistant to ciprofloxacin. The resistance rates to quinolons were as follows: nalidixic acid(48.7%), ofloxacin(29%), norfloxacin (27.7%), levofloxacin (23.7%). Seventy three (32.6%) isolates carried qnrB gene, whereas qnrA gene was not observed in any samples. As the study results indicated, resistant genes to qnrB were seen in the E. coli isolates of urine samples. As a matter of fact, a significant correlation was detected between qnrB gene and resistance to ciprofloxacin (p< 0/05). Moreover, antimicrobial susceptibility tests are recommended to be performed before beginning the treatment due to the increased resistance of E. coli to beta-lactams.