Department of Epizootiology and Clinic of Infectious Diseases, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Lublin, Poland.
Department of Epizootiology and Clinic of Infectious Diseases, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Lublin, Poland.
J Equine Vet Sci. 2020 Aug;91:103114. doi: 10.1016/j.jevs.2020.103114. Epub 2020 May 7.
Rhodococcus equi is an opportunistic, intracellular saprophyte that causes severe pyogranulomatous pneumonia in foals. The bacterium displays in vitro susceptibility to many antibiotics. The highest efficacy against R. equi in vitro and in vivo is achieved by using a combination of rifampicin and macrolide antibiotics. Recent years have seen an upward trend in the minimum inhibitory concentration (MIC) of rifampicin and erythromycin, suggesting increasing resistance of R. equi to these antibiotics. The aim of the study was to determine the antimicrobial activity of 24 selected antibiotics against R. equi strains isolated from dead foals and from the environment of horse breeding farms with and without endemic R. equi infections. Minimum inhibitory concentration gradient strips were used to determine the lowest concentration of the antibiotic that inhibited the growth of R. equi. Based on normal MIC distribution, an epidemiologic cutoff values (ECOFF) were assessed for particular antibiotics and R. equi strains. The results were compared with ECOFFs for S. aureus, according to the European Committee on Antimicrobial Susceptibility Testing data. The data indicate that the lowest MIC values were obtained for clarithromycin, rifampicin, imipenem, and vancomycin. The majority of R. equi strains can be classified as wild type in relation to the majority of antibiotics. A small percentage of strains presented non-WT (NWT) with the exception of SXT, for which 35% of strains were classified as NWT. The lack of interpretative criteria for R. equi creates a real problem in the assessment of antibiotic sensitivity both for clinical and scientific purposes.
马红球菌是一种机会性的、细胞内的腐生菌，可导致幼驹发生严重的化脓性肉芽肿性肺炎。该细菌在体外对许多抗生素敏感。体外和体内对马红球菌最有效的疗效是使用利福平加大环内酯类抗生素的联合用药。近年来，利福平及红霉素的最低抑菌浓度（MIC）呈上升趋势，表明马红球菌对这些抗生素的耐药性逐渐增加。本研究旨在确定 24 种选定抗生素对从死亡幼驹和无地方性马红球菌感染及有地方性马红球菌感染的马养殖农场环境中分离的马红球菌菌株的抗菌活性。使用抗生素浓度梯度条来确定抑制马红球菌生长的最低抗生素浓度。根据正常 MIC 分布，评估了特定抗生素和马红球菌菌株的流行病学折点值（ECOFF）。将结果与根据欧洲抗菌药物敏感性试验委员会数据得出的金黄色葡萄球菌的 ECOFF 进行了比较。数据表明，最低 MIC 值为克拉霉素、利福平、亚胺培南和万古霉素。大多数马红球菌菌株对大多数抗生素可归类为野生型。少数菌株表现出非野生型（NWT），除 SXT 外，其中 35%的菌株被归类为 NWT。由于缺乏马红球菌的解释性判断标准，无论是临床还是科学目的，评估抗生素敏感性都存在实际问题。
