Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
Center for Water Quality Research (CWQR), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran.
Sci Rep. 2020 Mar 13;10(1):4658. doi: 10.1038/s41598-020-61604-z.
Clostridium difficile is a leading causative agent of hospital-acquired and community-acquired diarrhea in human. This study aims to characterize the predominant C. difficile strains, RT001 and 126, circulating in Iranian hospitals in relation to resistant phenotypes, the antibiotic resistance genes, and their genetic relatedness. A total number of 735 faecal specimens were collected from patients suspected of CDI in Tehran hospitals. Typing and subtyping of the strains were performed using CE-PCR ribotyping and MLVA, respectively, followed by PCR assays for ARGs and indicators of Tns. Minimum inhibitory concentrations (MICs) of five antibiotics were determined by MIC Test Strips. Among 65 strains recovered from CDI patients, RT001 (32.3%) and RT126 (9.2%) were found as the most frequent ribotypes, and 64 MLVA types were identified. Using MLVA, RT001 and RT126 were subtyped into 6 and 4 groups, respectively. The vanA, nim, tetM, gyrA, gyrB genes were detected in 24.6%, 0%, 89.2%, 95.3%, and 92.3% of the strains, respectively. The indicators of Tns including vanHAX, tndX, and int were found in 0%, 3% and 29.2% of the strains, respectively. The most common amino acid (AA) alterations of GyrA and GyrB were related to substitutions of Thr82 → Val and Ser366 → Val, respectively. Resistance rate to metronidazole, vancomycin, tetracycline, ciprofloxacin, and moxifloxacin was 81.5%, 30.7%, 85%, 79%, and 74%, respectively. This study, for the first time revealed the subtypes of circulating RT001 and RT126 in Iran. It is of importance that the majority of the strains belonging to RT001 were multidrug resistant (MDR). This study also pointed to the intra-hospital dissemination of the strains belonging to RT001 and RT126 for short and long periods, respectively, using MLVA. The most important resistance phenotypes observed in this study was vancomycin-resistant phenotypes. Resistance to metronidazole was also high and highlights the need to determine its resistance mechanisms in the future studies.
艰难梭菌是导致人类医院获得性和社区获得性腹泻的主要病原体。本研究旨在对伊朗医院中流行的艰难梭菌主要菌株 RT001 和 126 进行特征描述，包括耐药表型、抗生素耐药基因及其遗传相关性。从德黑兰医院疑似 CDI 患者中收集了 735 份粪便标本。使用 CE-PCR 核糖体分型和 MLVA 分别对菌株进行分型和亚型分析，然后通过 PCR 检测 ARGs 和 Tns 标志物。采用 MIC Test Strips 测定五种抗生素的最低抑菌浓度（MIC）。从 CDI 患者中分离出的 65 株菌株中，RT001（32.3%）和 RT126（9.2%）为最常见的核糖体型，共鉴定出 64 种 MLVA 型。使用 MLVA，RT001 和 RT126 分别分为 6 组和 4 组。24.6%、0%、89.2%、95.3%和 92.3%的菌株检测到 vanA、nim、tetM、gyrA 和 gyrB 基因。菌株中 vanHAX、tndX 和 int 的 Tns 标志物分别为 0%、3%和 29.2%。GyrA 和 GyrB 最常见的氨基酸（AA）改变与 Thr82→Val 和 Ser366→Val 的取代有关。甲硝唑、万古霉素、四环素、环丙沙星和莫西沙星的耐药率分别为 81.5%、30.7%、85%、79%和 74%。本研究首次揭示了伊朗流行的 RT001 和 RT126 的亚型。重要的是，属于 RT001 的大多数菌株为多药耐药（MDR）。本研究还通过 MLVA 表明，属于 RT001 和 RT126 的菌株在短时间和长时间内分别在医院内传播。本研究中观察到的最重要的耐药表型是万古霉素耐药表型。甲硝唑耐药率也很高，这表明在未来的研究中需要确定其耐药机制。
