Determination of antibiotic resistance genes and virulence factors in Escherichia coli isolated from Turkish patients with urinary tract infection

Abstract INTRODUCTION : Escherichia coli ranks among the most common sources of urinary tract infections (UTI). METHODS: Between November 2015 and August 2016, 90 isolates of E. coli were isolated from patients at Rize Education and Research Hospital in Turkey. Antibiotic susceptibility was determined for all isolates using the Kirby-Bauer disk diffusion method. These E. coli isolates were also screened for virulence genes, β-lactamase coding genes, quinolone resistance genes, and class 1 integrons by PCR. RESULTS: With respect to the antibiotic resistance profile, imipenem and meropenem were effective against 98% and 90% of isolates, respectively. A high percentage of the isolates showed resistance against β lactam/β lactamase inhibitor combinations, quinolones, and cephalosporins. PCR results revealed that 63% (57/90) of the strains carried class 1 integrons. In addition, a high predominance of extended-spectrum β-lactamases (ESBLs) was observed. The qnrA, qnrB, and qnrS genes were found in 24 (26.6%), 6 (6.6%), and 3 (3.3%), isolates, respectively. The most common virulence gene was fim (82.2%).The afa, hly, and cnf1 genes were detected in 16.6%, 16.6%, and 3.3% of isolates, respectively. Moreover, we observed eleven different virulence patterns in the 90 E. coli isolates. The most prevalent pattern was fım, while hly-fım, afa-aer-cnf-fım, aer-cnf, afa-aer, and afa-cnf-fım patterns were less common. CONCLUSIONS: Most of the E. coli virulence genes investigated in this study were observed in E. coli isolates from UTI patients. Virulence genes are very important for the establishment and maintenance of infection.

【摘要】
引言：大肠埃希菌（Escherichia coli）是尿路感染（UTI）最常见的致病菌之一。
方法：2015年11月至2016年8月期间，研究人员从土耳其里泽教育与研究医院的患者样本中分离得到90株大肠埃希菌。采用柯比-鲍尔纸片扩散法（Kirby-Bauer disk diffusion method）对所有分离株进行抗菌药物敏感性试验。同时，通过聚合酶链反应（PCR）对上述大肠埃希菌分离株的毒力基因、β-内酰胺酶编码基因、喹诺酮类耐药基因及1类整合子（class 1 integrons）进行筛查。
结果：从耐药谱来看，亚胺培南和美罗培南分别对98%和90%的分离株具有抗菌活性。多数分离株对β-内酰胺类/β-内酰胺酶抑制剂复合制剂、喹诺酮类及头孢菌素类药物表现出耐药性。PCR检测结果显示，63%（57/90）的菌株携带1类整合子。此外，超广谱β-内酰胺酶（ESBLs）的检出率较高。qnrA、qnrB及qnrS基因的检出率分别为26.6%（24/90）、6.6%（6/90）及3.3%（3/90）。最常见的毒力基因为fim基因，检出率达82.2%。afa、hly及cnf1基因的检出率分别为16.6%、16.6%及3.3%。此外，在90株大肠埃希菌分离株中共观察到11种不同的毒力基因型模式，其中以fim模式最为普遍，而hly-fim、afa-aer-cnf-fim、aer-cnf、afa-aer及afa-cnf-fim模式相对少见。
结论：本研究中检测的多数大肠埃希菌毒力基因均存在于尿路感染患者分离的大肠埃希菌菌株中。毒力基因对于感染的建立与维持具有至关重要的作用。