شیوع و مکانیسم های مقاومت به سیپروفلوکسازیندر ایزوله های اشریشیا کلی جدا شده از بیماران،حاملین سالم و فاضلاب در اردبیل

عنوان انگليسی

Prevalence and mechanisms of ciprofloxacin resistance in Escherichia coli isolated from hospitalized patients, healthy carriers, and wastewaters in Iran

خلاصه انگلیسی

Background This study was aimed to evaluate the prevalence and molecular characteristics of ciprofoxacin resistance among 346 Escherichia coli isolates collected from clinical specimens (n=82), healthy children (n=176), municipal wastewater (n=34), hospital wastewater (n=33), poultry slaughterhouse wastewater (n=12) and livestock (n=9) slaughterhouse wastewater in Iran. Methods Ciprofoxacin minimum inhibitory concentration (MIC) was determined by agar dilution assay. Phylogroups and plasmid-mediated quinolone resistance (PMQR) genes were identifed using PCR. Mutations in gyrA, gyrB, parC, and parE genes and amino acid alterations were screened through sequencing assay. The efect of efux pump inhibitor (PAβN) on ciprofoxacin MICs in ciprofoxacin-resistant isolates was investigated using the microdilution method. Results In total, 28.03% of E. coli isolates were phenotypically resistant to ciprofoxacin. Based on sources of isolation, 64.63%, 51.51%, 33.33%, 14.70%, 10.22% and 8.33% of isolates from clinical specimens, hospital wastewater, livestock wastewater, municipal wastewater, healthy children and poultry wastewater were ciprofoxacin-resistant, respectively. Eighty-one point eighty-one percent (Ser-83→Leu+Asp-87→Asn; 78.78% and Ser-83→Leu only; 3.03% (of ciprofoxacin-resistant E. coli isolates showed missense mutation in GyrA subunit of DNA gyrase, while no aminoacid substitution was noted in the GyrB subunit. DNA sequence analyses of the ParC and ParE subunits of topoisomerase IV exhibited amino-acid changes in 30.30% (Ser-80→Ile+Glu-84→Val; 18.18%, Ser-80→Ile only; 9.10% and Glu-84→Val only; 3.03%0 (and 15.38% (Ser-458→Ala) of ciprofoxacin-resistant E. coli isolates, respectively. The PMQR genes, aac(6’)-Ib-cr, qnrS, qnrB, oqxA, oqxB, and qepA were detected in 43.29%, 74.22%, 9.27%, 14.43%, 30.92% and 1.03% of ciprofoxacin-resistant isolates, respectively. No isolate was found to be positive for qnrA and qnrD genes. In isolates harboring the OqxA/B efux pump, the MIC of ciprofoxacin was reduced twofold in the presence of PAβN, as an efux pump inhibitor. The phylogroups B2 (48.45%) and A (20.65%) were the most predominant groups identifed in ciprofoxacin-resistant isolates. Conclusions This study proved the high incidence of ciprofoxacin-resistant E. coli isolates in both clinical and nonclinical settings in Iran. Chromosomal gene mutations and PMQR genes were identifed in ciprofoxacin resistance among E. coli population

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