title: Erythromycin resistance and virulence genes in Enterococcus faecalis from swine in China.
abstract: 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.
authors.affiliation: School of Life Science, Sichuan University, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu , China.
authors.forename: Li-Kou
authors.initials: LK
authors.lastname: Zou
authors.forename: Hong-Ning
authors.initials: HN
authors.lastname: Wang
authors.forename: Bo
authors.initials: B
authors.lastname: Zeng
authors.forename: Jin-Niang
authors.initials: JN
authors.lastname: Li
authors.forename: Xu-Ting
authors.initials: XT
authors.lastname: Li
authors.forename: An-Yun
authors.initials: AY
authors.lastname: Zhang
authors.forename: Ying-Shun
authors.initials: YS
authors.lastname: Zhou
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.forename: Chang-Wen
authors.initials: CW
authors.lastname: Xu
authors.forename: Qing-Qing
authors.initials: QQ
authors.lastname: Xia
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002681:China; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D004917:Erythromycin / Q000494:pharmacology*; D005838:Genotype; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D013552:Swine; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D037521:Virulence Factors; D004917:Erythromycin