Mahmoudi-Aznaveh Azam, Bakhshi Bita, Najar-Peerayeh Shahin
a Faculty of Medical Sciences, Department of Bacteriology , Tarbiat Modares University , Tehran , Iran.
J Chemother. 2017 Feb;29(1):1-7. doi: 10.1080/1120009X.2016.1154683. Epub 2016 Apr 11.
The aim of this study was to investigate the prevalence of multidrug resistance (MDR) in atypical enteropathogenic Escherichia coli (EPEC) genotypes among 547 diarrheal children. All E. coli isolates with eaestx1stx2 genotypes included in this study and atypical property of EPEC was characterized by the absence of Bundle-forming pili (bfpA gene). Bacterial pathogens were detected in 70 patients (12.8%) among which atypical EPEC (5.3%) were the most common. The higher resistance rate was seen to tetracycline (70%), cotrimoxazole (60%) and nalidixic acid (53.3%) related to MDR phenotype in 63.3% of isolates. The presence of class 1 and 2 integrons was 30% and 6.6% with the dominance of dfrA, aadA gene cassettes among the isolates. Eleven out of 21 phenotypically tetracycline-resistant isolates (52.38%) harboured one or two tetracycline resistance genes (A-D) which shows the incapability of known data to reasonable tetracycline resistance phenotypes among EPEC isolates. A high level of genotypic diversity was seen among the isolates by Pulsed-field gel electrophoresis method which ranged from 89.7 to 29% and no clear correlation was obtained between tetracycline resistance or integron carriage and specific pulsotypes. In conclusion, the data presented here add to knowledge about the heterogeneous nature of MDR EPEC population in Iran which has a growing tendency towards atypical genotypes. The distribution of integrons among EPEC isolates in Iran is decreasing; although, the resistance gene content is almost stable through years.
本研究旨在调查547名腹泻儿童中不典型肠致病性大肠杆菌（EPEC）基因型的多重耐药（MDR）流行情况。本研究纳入的所有具有eaestx1stx2基因型的大肠杆菌分离株，其EPEC的非典型特性表现为缺乏束状菌毛（bfpA基因）。70名患者（12.8%）检测出细菌病原体，其中最常见的是不典型EPEC（5.3%）。63.3%的分离株对四环素（70%）、复方新诺明（60%）和萘啶酸（53.3%）的耐药率较高，与MDR表型相关。1类和2类整合子的存在率分别为30%和6.6%，分离株中dfrA、aadA基因盒占主导。21株表型耐四环素的分离株中有11株（52.38%）携带一或两个四环素耐药基因（A - D），这表明已知数据无法合理解释EPEC分离株中的四环素耐药表型。通过脉冲场凝胶电泳法在分离株中观察到高度的基因多样性，范围从89.7%到29%，四环素耐药或整合子携带与特定脉冲型之间未获得明显相关性。总之，此处呈现的数据增加了对伊朗MDR EPEC群体异质性的认识，该群体向非典型基因型的趋势不断增加。伊朗EPEC分离株中整合子的分布正在减少；尽管如此，多年来耐药基因含量几乎稳定。
