Shiga toxin‐producing Escherichia coli (STEC) are among common foodborne bacterial pathogens and healthy livestock are the main source of this bacterium. Severe diseases attribute to two types of cytotoxin Stx1 and Stx2, which are also called Shiga toxin (Stx). Infection of humans with STEC may result in Acute diarrhea with or without bleeding, hemorrhagic colitis (HC) and the hemolytic uremic syndrome (HUS). As antibiotic resistance is increasingly being reported among STEC isolates obtained from livestock and patients worldwide, in this study the pattern of antibiotic resistance in clinical isolates was determined. Stool samples were collected from patients with diarrhea. All samples were cultured and identified by biochemical and molecular tests. Antimicrobial susceptibility test and assessment of extended-spectrum β-lactamase (ESBL)-related genes were conducted. Moreover, phylogenetic groups were analyzed using quadruplex PCR, and DNA analysis assessed multi-locus sequence types (MLST). Out of 340 E. coli samples, 174 were identified as STEC by PCR. Antimicrobial susceptibility test results showed that, 99.4%, 96% and 93.1% of isolates were susceptible to imipenem/ertapenem, piperacillin–tazobactam and amikacin, respectively. The highest resistance was towards ampicillin (68.4%), followed by trimethoprim–sulfamethoxazole (59.8%), and tetracycline (57.5%). A total of 106 (60.9%) isolates were multidrug resistance (MDR) and 40.8% of isolates were determined to be extended spectrum β-lactamase producers. In 94.4% of isolates, genes responsible for ESBL production could be detected, and blaTEM was the most prevalent, followed by blaCTX-M9. Furthermore, phylogenetic grouping revealed that majority of STEC strains belonged to Group C, followed by Groups E, B2 and A. MLST unveiled diverse ST types. A periodical surveillance studies and thorough understanding of antibiotic resistant profiles in STEC isolates could help select effective antibiotic treatment for patients and develop strategies to effectively manage food contamination and human infections.

中文翻译：

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从伊朗腹泻患者中分离出的产志贺毒素大肠杆菌的抗菌敏感性、超广谱 β-内酰胺酶基因和系统发育组的特征

产志贺毒素大肠杆菌 (STEC) 是常见的食源性细菌病原体之一，健康的家畜是这种细菌的主要来源。严重的疾病归因于两种细胞毒素 Stx1 和 Stx2，它们也称为志贺毒素 (Stx)。人类感染 STEC 可能导致伴有或不伴有出血的急性腹泻、出血性结肠炎 (HC) 和溶血性尿毒症综合征 (HUS)。由于从全世界的牲畜和患者中获得的 STEC 分离株中越来越多地报道了抗生素耐药性，因此在本研究中，确定了临床分离株中抗生素耐药性的模式。从腹泻患者收集粪便样本。所有样品均通过生化和分子检测进行培养和鉴定。进行了抗菌药物敏感性试验和超广谱β-内酰胺酶（ESBL）相关基因的评估。此外，系统发育组使用四重 PCR 进行分析，DNA 分析评估多位点序列类型 (MLST)。在 340 份大肠杆菌样本中，有 174 份经 PCR 鉴定为 STEC。抗菌药物敏感性试验结果表明，99.4%、96%和93.1%的分离株对亚胺培南/厄他培南、哌拉西林-他唑巴坦和阿米卡星敏感。对氨苄青霉素的耐药性最高（68.4%），其次是甲氧苄啶-磺胺甲恶唑（59.8%）和四环素（57.5%）。共有 106 (60.9%) 株分离株具有多重耐药性 (MDR)，40.8% 的分离株被确定为超广谱 β-内酰胺酶生产者。在 94.4% 的分离株中，可以检测到负责 ESBL 产生的基因，blaTEM 最为普遍，其次是 blaCTX-M9。此外，系统发育分组显示大多数 STEC 菌株属于 C 组，其次是 E、B2 和 A 组。MLST 揭示了不同的 ST 类型。定期监测研究和对 STEC 分离株中抗生素耐药性的透彻了解有助于为患者选择有效的抗生素治疗方法，并制定有效管理食品污染和人类感染的策略。