Abstract

Due to their antimicrobial activity Enterococcus faecium strains have a growing record of use as beneficial adjunct cultures in animal nutrition or components of probiotic preparations for humans. However, safety concerns accompany the application of enterococci, as clinical strains associated with infection have been isolated, especially antibiotic resistant cultures. With the increasing availability of whole genome sequencing (WGS), valuable safety data can be extracted in the early phase of development of the probiotic dossier of an E. faecium strain. Here we report the results of initial safety assessment of E. faecium LBB.E81 by selecting accessible commercial antibiotic susceptibility test and WGS. Testing against a panel of antibiotic substances showed that E. faecium LBB.E81 was susceptible to all antimicrobials with the exception of its intrinsic, non-transferable resistance to nitrofurantoin. The identified antibiotic resistance genes of E. faecium LBB.E81 aac(6')-Ii, msrC and efmA belonged to a group of intrinsic non-transferable factors contributing to the lower susceptibility of the E. faecium species to aminoglycoside and macrolide antibiotics but with minimal inhibitory concentrations for E. faecium LBB.E81 below the threshold values determined for resistant strains. The only potential virulence factor genes found in the genome of E. faecium LBB.E81 were a defective acm (collagen-binding adhesin) and efaA _fm (antigen A – like protein) without any evidence for its involvement in pathogenicity. Other hospital associated virulence factor genes of E. faecium such as IS16, hyl, asa-type genes, cyl; gelE and fsr, sprE and esp(fm) were found to be absent in E. faecium LBB.E81.

摘要

由于它们的抗微生物活性，粪肠球菌菌株在动物营养或人类益生菌制剂的成分中作为有益的辅助培养物的使用越来越多。然而，由于已经分离出与感染相关的临床菌株，尤其是抗生素抗性培养物，因此肠球菌的应用伴随着安全性问题。随着全基因组测序（WGS）可用性的提高，可以在粪肠球菌菌株的益生菌档案开发的早期阶段提取有价值的安全数据。在这里，我们报告粪肠球菌的初步安全性评估结果通过选择可访问的商业抗生素敏感性测试和WGS进行LBB.E81。对一组抗生素物质的测试表明，粪肠球菌LBB.E81除对内呋喃妥因的固有，不可转移的耐药性外，均对所有抗菌药物敏感。粪肠球菌LBB.E81 aac（6'）-Ii，msr C和efm A的已鉴定抗生素抗性基因属于一组固有的不可转移因子，这些粪肠球菌对氨基糖苷和大环内酯类药物的敏感性较低。抗生素，但对屎肠球菌的抑制浓度极低LBB.E81低于为抗性菌株确定的阈值。在粪肠球菌LBB.E81基因组中发现的唯一潜在的致病因子基因是有缺陷的acm（胶原结合粘附素）和efa A _fm（抗原A –类似蛋白），而没有任何证据表明其参与致病性。粪肠球菌的其他医院相关毒力因子基因，例如IS 16，hyl，asa型基因，cyl；发现屎肠球菌LBB.E81中不存在gelE和fsr，sprE和e sp（fm）。