Sedighi Iraj, Arabestani Mohammad Reza, Rahimbakhsh Ali, Karimitabar Zahra, Alikhani Mohammad Yousef
Department of Pediatric, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, IR Iran.
Department of Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, IR Iran ; Brucellosis Research Center, Hamadan University of Medical Sciences, Hamadan, IR Iran.
Jundishapur J Microbiol. 2015 Jul 25;8(7):e19184. doi: 10.5812/jjm.19184v2. eCollection 2015 Jul.
Urinary tract infection (UTI) is one of the most common childhood bacterial infections and Escherichia coli is the major pathogen. Producing β-lactamase enzymes are the most common mechanism of bacterial resistance.
This study aimed to determine the prevalence of Extended-Spectrum β-Lactamases (ESBLs) and Quinolone Resistance (qnr) genes in E. coli strains isolated from UTIs.
In this study, a total of 120 isolates of E. coli from urinary tract infections of the children were collected at Besat Hospital in Hamadan, Iran, from October 2010 to October 2011. The bacterial isolates were identified by standard biochemical methods. Antimicrobial susceptibilities were determined by disk diffusion method, and ESBLs-producing was confirmed phenotypically using the double-disk synergy (DDS) test. The presence and identification of ESBLs and qnr genes were determined by Polymerase Chain Reaction (PCR).
The highest sensitivity was seen to imipenem (96.7%), amikacin (92.5%), nitrofurantoin (93.3%), ofloxacin (81.7%), gentamicin norfloxacin (70.8%), and ciprofloxacin (79.2%). In contrast, the highest rate of resistance was seen to co-trimoxazole (77%) and nalidixic acid (40.9%). The results showed that 6 (2.18%) and 4 (1.12%) isolates of ESBL-producing E. coli were positive with respect to having qnrB and qnrS genes, respectively. No isolates was found to have qnrA.
CTX-M was the most prevalent ESBL genotype in uropathogenic E. coli (UPEC) isolated from UTI. In addition, a high frequency of qnr genes among ESBL-producing E. coli was identified in this study. In order to avoid treatment failures, we recommend using phenotypic and molecular methods to diagnose these enzymes and qnr genes.
尿路感染（UTI）是儿童最常见的细菌性感染之一，大肠杆菌是主要病原体。产生β-内酰胺酶是细菌耐药的最常见机制。
本研究旨在确定从尿路感染分离出的大肠杆菌菌株中广谱β-内酰胺酶（ESBLs）和喹诺酮耐药（qnr）基因的流行情况。
本研究于2010年10月至2011年10月在伊朗哈马丹的贝萨特医院收集了120株来自儿童尿路感染的大肠杆菌分离株。通过标准生化方法鉴定细菌分离株。采用纸片扩散法测定抗菌药物敏感性，并使用双纸片协同（DDS）试验从表型上确认产ESBLs情况。通过聚合酶链反应（PCR）确定ESBLs和qnr基因的存在及鉴定。
对亚胺培南（96.7%）、阿米卡星（92.5%）、呋喃妥因（93.3%）、氧氟沙星（81.7%）、庆大霉素诺氟沙星（70.8%）和环丙沙星（79.2%）的敏感性最高。相比之下，对复方新诺明（77%）和萘啶酸（40.9%）的耐药率最高。结果显示，产ESBLs的大肠杆菌分离株中分别有6株（2.18%）和4株（1.12%）的qnrB和qnrS基因呈阳性。未发现有qnrA的分离株。
CTX-M是从尿路感染分离出的尿路致病性大肠杆菌（UPEC）中最常见的ESBL基因型。此外，本研究发现产ESBLs的大肠杆菌中qnr基因频率较高。为避免治疗失败，我们建议使用表型和分子方法来诊断这些酶和qnr基因。
