Evaluation of 15 Motility Media and a Direct Microscopic Method for Detection of Motility in Enterococci

Isolation of motile, vanC enterococci has yet to be a major infection control concern; however, rapid detection still is important. We evaluated 15 motility media from three manufacturers and a 2-h direct microscopic method for accurate detection of 89 enterococcal strains, including 72 vanC enterococcal strains. Resistance genes were confirmed by a multiplex PCR method with the vanC gene detected in all motile enterococci. Motility in the 72 vanC enterococci was detected at 30°C within 72 h in BD Biosciences motility nitrate medium and in Remel motility B medium, motility B medium supplemented with methyl-α-d-glucopyranoside (investigational), motility S medium, motility test medium, and motility test medium with tetrazolium indicator. Motility was also observed for all vanC enterococci with the 2-h direct (30°C incubation) microscopic detection method. All Enterococcus faecalis and Enterococcus faecium isolates were observed to be nonmotile in all media and by the direct microscopic method. Since differences between the various motility media tested were observed, the medium used for detection of enterococcal motility must be selected carefully.

可运动vanC型肠球菌（vanC enterococci）的分离目前尚未成为感染防控的主要关注点，但快速检测仍具有重要意义。本研究评估了来自3家生产商的15种运动性培养基，以及一种耗时2小时的直接镜检法，用于精准检测89株肠球菌，其中包含72株vanC型肠球菌。耐药基因经多重PCR（multiplex PCR）法验证，所有可运动肠球菌均检出vanC基因。在72株vanC型肠球菌中，于30℃培养72小时内，可在BD Biosciences运动性硝酸盐培养基、Remel运动性B培养基、添加甲基-α-D-吡喃葡萄糖苷的运动性B培养基（研究用）、运动性S培养基、运动性检测培养基以及含四唑鎓指示剂的运动性检测培养基中检出运动性。采用2小时直接镜检法（30℃培养）也可检出所有vanC型肠球菌的运动性。粪肠球菌（Enterococcus faecalis）和屎肠球菌（Enterococcus faecium）的所有分离株，在所有培养基中以及通过直接镜检法均被证实无运动性。鉴于本次测试的不同运动性培养基间存在性能差异，用于肠球菌运动性检测的培养基需谨慎选择。