Veterinary School. Federal University of Minas Gerais, Antônio Carlos Avenue, 6627. Belo, Horizonte, MG, 31.270-901, Brazil.
School of Medicine. Federal University of Minas Gerais, Prof. Alfredo Balena Avenue, 190. Belo, Horizonte, MG, 30.130-100, Brazil.
Anaerobe. 2023 Apr;80:102720. doi: 10.1016/j.anaerobe.2023.102720. Epub 2023 Mar 18.
Antimicrobial resistance (AMR) is one of the greatest threats to animal and public health. Clostridioides (prev. Clostridium) difficile is a major burden to healthcare and a relevant AMR gene reservoir. Despite the known importance of AMR in C. difficile epidemiology and treatment, antimicrobial susceptibility testing for this pathogen is still based on the determination of the minimal inhibitory concentration (MIC) by the agar dilution method, which is technically demanding and labor-intensive. In this study, the disk diffusion method was used to evaluate the susceptibility of C. difficile to erythromycin, rifampicin, and tetracycline.
A total of 155 isolates isolated between 2011 and 2022 from humans and animals in Brazil were simultaneously tested using the disk diffusion method and the epsilometer test (Etest) for these three antimicrobials on Brucella blood agar supplemented with vitamin K and hemin.
The results suggest that disk diffusion can be an interesting routine tool to identify erythromycin- and rifampicin-resistant C. difficile isolates (≥20 mm cut-off) and wild type (WT) strains (≥28 mm). However, the disk diffusion protocol tested in this study does not seem suitable for tetracycline because of the common misclassification of resistant strains.
抗菌药物耐药性（AMR）是对动物和公共卫生的最大威胁之一。艰难梭菌（原名梭状芽孢杆菌）是医疗保健的主要负担，也是相关 AMR 基因库。尽管 AMR 在艰难梭菌流行病学和治疗中的重要性已得到证实，但对该病原体的抗菌药物敏感性测试仍然基于琼脂稀释法确定最小抑菌浓度（MIC），该方法技术要求高且劳动强度大。在这项研究中，使用纸片扩散法评估了艰难梭菌对红霉素、利福平、和四环素的敏感性。
本研究共检测了 155 株于 2011 年至 2022 年间从巴西人和动物中分离的菌株，同时使用纸片扩散法和埃希氏测试（Etest）在添加维生素 K 和血红素的布鲁氏血琼脂上对这三种抗生素进行检测。
结果表明，纸片扩散法可作为一种有前途的常规工具，用于鉴定红霉素和利福平耐药的艰难梭菌（≥20mm 截止值）和野生型（WT）菌株（≥28mm）。然而，本研究中测试的纸片扩散方案似乎不适合四环素，因为耐药菌株的常见错误分类。
