Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran; Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran; Laboratory Sciences Research Center, Golestan University of Medical Sciences, Gorgan, Iran.
Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
J Glob Antimicrob Resist. 2019 Sep;18:28-33. doi: 10.1016/j.jgar.2019.01.027. Epub 2019 Jan 28.
Clostridium difficile (C. difficile) is the main causative agent of antibiotic-associated diarrhoea (AAD) and pseudomembranous colitis. The accumulation of antimicrobial resistance in C. difficile strains can drive C. difficile infection (CDI) epidemiology. This study was undertaken to evaluate the antimicrobial resistance patterns of toxigenic C. difficile isolates cultured from diarrhoeal stool samples of hospitalised patients with suspected CDI in three tertiary care hospitals in Tehran, Iran.
Two hundred and fifty diarrhoeal stool samples were investigated by toxigenic culture using cycloserine-cefoxitin-fructose agar and the VERO cell line. Antimicrobial susceptibility to metronidazole, vancomycin, clindamycin, tetracycline, and moxifloxacin was performed by disk diffusion and Etest methods on Brucella Blood Agar supplemented with hemin and vitamin K.
Thirty-five stool samples (14.0%) proved positive using C. difficile toxigenic culture. According to Clinical and Laboratory Standards Institute breakpoints, the following resistance was identified in C. difficile isolates: metronidazole (2 of 35); moxifloxacin (7 of 35); clindamycin (18 of 35); and tetracycline (5 of 35). Using European Committee on Antimicrobial Susceptibility Testing breakpoints, three of 35 isolates showed reduced-susceptibility for vancomycin and 14 of 35 for metronidazole. In addition, the results showed a good correlation between the inhibition zone diameter (disk diffusion) and MIC values (Etest); Pearson correlation coefficient 0.7400.95 (P< 0.001).
Multidrug resistance was observed in Iranian clinical toxigenic C. difficile isolates, including reduced susceptibility to first-line CDI treatment drugs. In addition, disk diffusion can be used as a cost-effective option for the antimicrobial susceptibility testing of C. difficile isolates.
艰难梭菌（C. difficile）是抗生素相关性腹泻（AAD）和伪膜性结肠炎的主要病原体。艰难梭菌菌株中抗菌药物耐药性的积累可推动艰难梭菌感染（CDI）的流行病学发展。本研究旨在评估 3 家伊朗德黑兰三级护理医院疑似 CDI 住院患者腹泻粪便样本中培养的产毒艰难梭菌分离株的抗菌药物耐药模式。
采用环丝氨酸头孢西丁果糖琼脂和 VERO 细胞系对 250 份腹泻粪便样本进行产毒培养。采用纸片扩散法和 Etest 法对艰难梭菌分离株进行甲硝唑、万古霉素、克林霉素、四环素和莫西沙星的药敏试验，在添加有血红素和维生素 K 的 Brucella Blood Agar 上进行。
35 份粪便样本（14.0%）经艰难梭菌产毒培养阳性。根据临床和实验室标准协会（CLSI）的折点，在艰难梭菌分离株中发现以下耐药性：甲硝唑（35 株中的 2 株）；莫西沙星（35 株中的 7 株）；克林霉素（35 株中的 18 株）；四环素（35 株中的 5 株）。根据欧洲抗菌药物敏感性试验委员会（EUCAST）的折点，35 株分离株中有 3 株对万古霉素的敏感性降低，14 株对甲硝唑的敏感性降低。此外，结果表明抑菌圈直径（纸片扩散法）与 MIC 值（Etest）之间存在良好的相关性；皮尔逊相关系数 0.7400.95（P<0.001）。
在伊朗临床产毒艰难梭菌分离株中观察到了多药耐药性，包括对一线 CDI 治疗药物的敏感性降低。此外，纸片扩散法可作为艰难梭菌分离株抗菌药物敏感性试验的一种经济有效的选择。
