| ORIGINAL ARTICLE |
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| Year : 2016 | Volume
: 4
| Issue : 1 | Page : 5-9 |
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Presence of Qnr genes related to resistance to quinolones, first-, second- and third-generation in diarrhoeagenic Escherichia coli
Abbas Mokhtari-Farsani1, Abbas Doosti2, Zahra Mohammadalipour2
1 Young Researchers and Elite Club, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran
2 Biotechnology Research Center, Islamic Azad University, Shahrekord Branch, Shahrekord, Iran
Correspondence Address:
Abbas Doosti
Biotechnology Research Center, Islamic Azad University, Shahrekord Branch, P.O. Box 166, Shahrekord
Iran
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/2214-207X.203541
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Background: Resistance genes transferred by plasmids are important factors that can contribute to the occurrence of quinolone resistance, specifically in Escherichia coli strains.
Methods: A total number of 117 diarrhoeagenic E. coli strains were tested for the resistance to nalidixic acid, ofloxacin, ciprofloxacin and levofloxacin and for the presence of qnrA, qnrB and qnrS genes determinants by polymerase chain reaction. Antibiotic susceptibility test was performed using the Clinical and Laboratory Standard Institute standard method.
Results: The highest resistance belonged to the nalidixic acid (52.14%) and the least resistance to levofloxacin (37.61%). In this study, among a total of 117 samples, 23 (19.66%) strains were susceptible to all the studied antibiotics. Among the remainder, 94 (80.34%) samples resistant to at least one quinolone, three genes including qnrA, qnrB and qnrS were present in 19.15%, 88.30% and 78.72% isolates, respectively. Furthermore, 51.06% of strains had A−, B+ and S+ pattern that seems to have a significant association (P < 0.001) with resistance to quinolones.
Conclusions: The results of present study show the presence of a high frequency of qnr genes in E. coli strains resistant to quinolones in clinical samples from southwest of Iran. In addition, this study approved that plasmid-mediated quinolone resistance is a possible mechanism among the quinolones-resistant E. coli isolated from patients with diarrhoea in the study, and also qnrB and qnrS genes seem to be more important in resistance to quinolones.
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