Brachyspira hyodysenteriae and Brachyspira pilosicoli cause economically important enteric disease in pigs. Treatment of these infections often includes antimicrobial administration, which can be most effective when therapeutic options are informed by antimicrobial susceptibility testing data. Here we describe a method for broth dilution antimicrobial susceptibility testing of these bacteria, both of which are difficult to culture in vitro. The protocol was evaluated for its fitness for use in an inter-laboratory ring trial involving eight laboratories from seven countries, and employing eleven test strains (5 Brachyspira hyodysenteriae including the type strain B78T and 6 Brachyspira pilosicoli) and six antibiotics. Overall intra- and inter-laboratory reproducibility of this method was very good (>90 % MICs at mode +/- 1 log2). Whole genome sequencing revealed good correspondence between reduced susceptibility and the presence of previously defined antimicrobial resistance determinants. Interestingly, lnu(C) was identified in B. pilosicoli isolates with elevated MICs of lincomycin, whilst tva(B) was associated with elevated MICs of pleuromutilins in this species. We designated two new control strains with MICs lying within currently tested ranges, including for the pleuromutilins, in contrast to the control strain B. hyodysenteriae B78T. These were deposited at the DSMZ-German Collection of Microorganisms and Cell Cultures GmbH. The validation of a standard protocol and identification of new control strains facilitates comparisons between studies, establishment of robust interpretative criteria, and ultimately contributes to rational antimicrobial use when treating infected livestock.

中文翻译：

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在国际环试验中验证了猪痢疾短螺旋体和猪痢疾短螺旋体的药敏试验方法的有效性。

猪痢疾短螺旋体和短螺旋体引起经济上重要的肠病。这些感染的治疗通常包括抗菌药物的施用，当通过抗菌药物敏感性测试数据提供治疗选择时，这可能是最有效的。在这里，我们描述了这些细菌的肉汤稀释抗药性测试的方法，这两种细菌都很难在体外培养。评估了该协议是否适合在实验室间的环试验中使用，该试验涉及来自七个国家的八个实验室，并使用了11种测试菌株（5种短螺旋体猪痢疾短螺旋体，包括B78T型菌株和6种短螺旋藻）和6种抗生素。此方法的整体实验室内和实验室间重现性非常好（模式+/- 1 log2时MIC大于90％）。全基因组测序显示药敏性降低与先前定义的抗药性决定因素之间存在良好的对应关系。有趣的是，在该物种中，在具有林可霉素MIC升高的B. pilosicoli分离物中鉴定了lnu（C），而在该物种中，tva（B）与截短侧耳素的MIC升高相关。与对照菌株猪痢疾短螺旋体B78T相比，我们指定了两种新的MIC，其MIC在当前测试范围内，包括截短侧耳素。这些被保藏在DSMZ-德国微生物和细胞培养有限公司收藏中。标准方案的验证和新控制菌株的鉴定有助于研究之间的比较，可靠的解释标准的建立，