Ebrahimi Mohammad Taha, Halimi Shahnaz, Yavari-Bafghi Maryam, Beigverdi Reza, Rahdar Hossein Ali, Emaneini Mohammad, Jabalameli Fereshteh
Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran.
Mol Biol Rep. 2025 Feb 5;52(1):206. doi: 10.1007/s11033-025-10310-y.
The multidrug-resistant clone identified as Escherichia coli sequence type 131 (E. coli ST131) has spread worldwide. The current study is one of the first comprehensive investigations to ascertain the prevalence of ST131 and molecularly characterize the ST131-O25b and ST131-O16 subgroups causing bloodstream infections in Iran.
To this end, 119 consecutive, non-repetitive E. coli clinical strains were isolated from blood samples of patients with septicemia in different hospital wards for one year in Tehran. The isolates were provided by the laboratories of tertiary hospitals affiliated with Tehran University of Medical Sciences. The disk diffusion method was used to investigate the sensitivity of bacteria to antibiotics. All phylogroup B2 isolates were screened for E. coli ST131 status using a triplex PCR assay that combines the identification of ST131-O25b and -O16 clades. The seven putative virulence factor genes (kpmstII, fimH, afa A, iroN, Sat, ibeA, and ompT) and resistance genes (bla, bla, and bla) were detected by PCR in E. coli ST131 isolates.
The highest incidence of antibiotic resistance among 74/119 (62.18%) extended-spectrum β-lactamases-producing E. coli isolates was observed, respectively, against Nalidixic acid (82%), and Aztreonam (75%), followed by Ciprofloxacin (70%). Twenty out of 74 ESBL-producing E. coli isolates were found to be ST131 (27%), with 13 (65%) ST131-O25b and 7 (35%) ST131-O16 clades, respectively. The ST131-O16 isolates had a higher prevalence of resistance to Ceftriaxone, Amikacin, Aztreonam, and Cefepime than the -O25b ones. Concerning virulence capacity, our findings demonstrated that kpmstII, fimH, and ompT genes were found in 85%, 65%, and 30% of ST131 isolates, respectively. Our results reinforce the surveillance of E. coli ST131 clone dissemination as a major drug-resistant pathogen and an important new public health threat in Iran. Accumulation of multiple virulence factors, ESBL carriage, and identified antimicrobial resistance patterns of ST131-O25b and ST131-O16 clones indicate a necessity to develop strategies to control the spread of these isolates in both community and hospital settings.
被鉴定为大肠杆菌序列型131（E. coli ST131）的多重耐药克隆已在全球传播。本研究是首批全面调查之一，旨在确定ST131的流行情况，并从分子层面表征在伊朗引起血流感染的ST131 - O25b和ST131 - O16亚组。
为此，在德黑兰，从不同医院病房的败血症患者血液样本中连续分离出119株非重复的大肠杆菌临床菌株，为期一年。这些分离株由德黑兰医科大学附属三级医院的实验室提供。采用纸片扩散法研究细菌对抗生素的敏感性。使用结合鉴定ST131 - O25b和 - O16分支的三重PCR检测法，对所有B2系统发育群分离株进行ST131状态筛查。通过PCR在大肠杆菌ST131分离株中检测7个假定的毒力因子基因（kpmstII、fimH、afa A、iroN、Sat、ibeA和ompT）和耐药基因（bla、bla和bla）。
在74/119（62.18%）产超广谱β - 内酰胺酶的大肠杆菌分离株中，观察到抗生素耐药率最高的分别是对萘啶酸（82%）和氨曲南（75%），其次是环丙沙星（70%）。在74株产ESBL的大肠杆菌分离株中，有20株被发现是ST131（27%），其中分别有13株（65%）属于ST131 - O25b分支和7株（35%）属于ST131 - O16分支。ST131 - O16分离株对头孢曲松、阿米卡星、氨曲南和头孢吡肟的耐药率高于 - O25b分离株。关于毒力，我们的研究结果表明，kpmstII、fimH和ompT基因分别在85%、65%和30%的ST131分离株中被发现。我们的结果强化了对大肠杆菌ST131克隆传播的监测，它是伊朗一种主要的耐药病原体和重要的新公共卫生威胁。多种毒力因子的积累、ESBL携带以及已确定的ST131 - O25b和ST131 - O16克隆的抗菌耐药模式表明，有必要制定策略来控制这些分离株在社区和医院环境中的传播。
