Zou Li-Kou, Wang Hong-Ning, Zeng Bo, Li Jin-Niang, Li Xu-Ting, Zhang An-Yun, Zhou Ying-Shun, Yang Xin, Xu Chang-Wen, Xia Qing-Qing
School of Life Science, Sichuan University, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu , China.
New Microbiol. 2011 Jan;34(1):73-80. Epub 2011 Jan 15.
This study aims to describe the erythromycin resistance phenotypes and genotypes, and the prevalence of virulence genes of Enterococcus faecalis isolated from swine in China. A total of 117 nonreplicate E. faecalis isolates, obtained from 502 clinical samples taken from different pig farms between 2007 and 2009 were included in the study. Minimum inhibitory concentrations were determined using the broth microdilution method. All of the isolates were screened for the presence of seven virulence genes (ace, asa1, cylA, efaA, esp, gelE, and hyl). In addition, the DNA from rythromycin-resistant isolates were amplified with primers specific for erythromycin resistance erm(A), erm(B), erm(C), mef(A/E), and msr(C) genes. Results show that erythromycin, tylosin, and ciprofloxacin resistance rates in E. faecalis were 66.67% (n=78), 66.67% (n=78), and 64.10% (n=75), respectively. About 69.23% of isolates (n=81) were positive for gelE, 48.72% (n=57) for ace, 15.38% (n=18) for efa, 7.69% (n=9) for asa1, and 6.84% (n=8) for esp. Among the erythromycin-resistant isolates, erm(B) (n=54) was the most prevalent resistance gene, followed by erm(A) (n=37). A significant correlation was found between the presence of the gelE virulence gene and erythromycin resistance (P<0.05). These findings suggest that enterococci from swine should be regarded with caution because they can be reservoirs for antimicrobial resistance and virulence genes.
本研究旨在描述从中国猪群中分离出的粪肠球菌的红霉素耐药表型和基因型，以及毒力基因的流行情况。本研究共纳入了117株非重复的粪肠球菌分离株，这些分离株取自2007年至2009年间不同猪场的502份临床样本。采用肉汤微量稀释法测定最低抑菌浓度。对所有分离株进行7种毒力基因（ace、asa1、cylA、efaA、esp、gelE和hyl）的筛选。此外，用针对红霉素耐药erm(A)、erm(B)、erm(C)、mef(A/E)和msr(C)基因的引物对红霉素耐药分离株的DNA进行扩增。结果显示，粪肠球菌对红霉素、泰乐菌素和环丙沙星的耐药率分别为66.67%（n = 78）、66.67%（n = 78）和64.10%（n = 75）。约69.23%的分离株（n = 81）gelE呈阳性，48.72%（n = 57）ace呈阳性，15.38%（n = 18）efa呈阳性，7.69%（n = 9）asa1呈阳性，6.84%（n = 8）esp呈阳性。在红霉素耐药分离株中，erm(B)（n = 54）是最常见的耐药基因，其次是erm(A)（n = 37）。发现gelE毒力基因的存在与红霉素耐药之间存在显著相关性（P<0.05）。这些发现表明，来自猪的肠球菌应谨慎对待，因为它们可能是抗菌药物耐药性和毒力基因的储存库。
