广东省养禽场肠球菌耐药性及毒力因子流行分布特征

旨在调查和分析广东省养禽场肠球菌的亚型屎肠球菌和粪肠球菌耐药性及其毒力因子流行分布特征，为控制禽源肠球菌耐药性传播、保障公共卫生安全提供理论依据。作者于2018年从广东省4个养禽场采集肠道样品493份，进行屎肠球菌和粪肠球菌的分离鉴定；采用琼脂二倍稀释法测定肠球菌的最小抑菌浓度（MIC）；PCR方法检测肠球菌的耐药基因和毒力基因。结果显示：1）共分离到125株肠球菌，其中粪肠球菌84株（鸡源66株，鸭源18株）；屎肠球菌41株，均来自鸡肠道样本。2）菌株对四环素、多西环素、红霉素几乎全部耐药，对氟苯尼考和氯霉素的耐药率高达89.60%和74.40%。屎肠球菌耐药率普遍高于粪肠球菌，而粪肠球菌对环丙沙星和利奈唑胺的耐药率高于屎肠球菌；鸭源粪肠球菌对利奈唑胺的耐药率（94%）显著高于鸡源粪肠球菌（39.4%），屎肠球菌对利奈唑胺均敏感。从鸡分离的1株粪肠球菌对万古霉素耐药。3）耐药基因在屎肠球菌中的检出率高于粪肠球菌，鸭源分离株检出率高于鸡源。耐药基因tetL、fexA、ermB最为流行，检出率均高于90%。其次是optrA基因，检出率为73.60%，poxtA和fexB的检出率均低于20%。在3株鸭源粪肠球菌中检测出cfr基因。4）已检测的毒力基因中efaA的携带率最高，为63.04%（58/92），其他依次为gelE（54.35%，50/92）、ace（47.83%，44/92）、asa1（44.57%，41/92）。对环丙沙星及高浓度氨基糖苷类耐药的菌株及携带cfr基因的菌株，大多携带agg、asal、gelE或ace。本研究显示养殖场禽源肠球菌耐药严重，鸭源肠球菌对利奈唑胺耐药率高，耐药基因和毒力基因流行且多样，且检测出人医临床重要抗生素耐药基因，应加强对养禽场肠球菌耐药性监测。

Prevalence of Antimicrobial Resistance and Virulence Factors in Enterococci from Poultry Farms in Guangdong Province

The subtypes, antimicrobial resistance, virulence genes of enterococci isolated from poultry farms in Guangdong province were investigated and analyzed, aimed to provide theoretical basis for the control of resistance spread of animal origin enterococci and public health. A total of 493 intestinal samples were collected from 4 poultry farms in Guangdong province in 2018 for isolation and identification of E. faecalis and E. faecium. All the isolates were characterized by antimicrobial susceptibility using the agar dilution method, detection of antimicrobial resistance genes and virulence genes by PCR. Results were as follows:1) The results showed that a total of 125 isolates were obtained, including 84 E. faecalis (66 from chicken and 18 from duck) and 41 E. faecium from chicken intestinal samples. 2) The strains were almost all resistant to tetracycline, doxycycline, erythromycin. The antimicrobial resistance rates of florfenicol and chloramphenicol were as high as 89.60% and 74.40%, respectively. In general, the antimicrobial resistance rate of E. faecium was higher than that of E. faecalis, and the resistance rate for ciprofloxacin and linezolid in E. faecalis was higher than that in E. faecium. The resistance rate to linezolid was significantly higher in E. faecalis from duck (94%) than that from chicken (39.4%). However, all E. faecium were susceptible to linezolid. One E. faecalis strain from the chicken sample was resistant to vancomycin. 3) The detection rate for resistant genes in E. faecium was higher than that in E. faecalis, and the detection rate in duck isolates was higher than that in chicken isolates. Genes tetL, fexA and ermB were the most popular, with detection rates above 90%, followed by optrA (73.60%), and poxtA and fexB, being less than 20%. The cfr gene was detected in 3 E. faecalis from duck. 4) Among virulence genes tested, efaA was the most prevalent, with a detection rate of 63.04% (58/92), followed by gelE (54.35%, 50/92), ace (47.83%, 44/92) and asal (44.57%, 41/92). The strains resistant to CIP and HLAR and those harboring cfr mostly carried the virulence genes aggA, asal, gelE or ace. Enterococci from poultry farms presented serious antimicrobial resistance, and particularly strains from ducks demonstrated a high resistance rate to Linezolid. Antimicrobial-resistant genes and virulence genes are prevalent and diverse. Genes conferring resistance antimicrobials relevant to human medicine have also been detected. Therefore, it is necessary to strengthen the monitoring of enterococci resistance in poultry farms.