College of Veterinary Medicine and Zoonoses Research Institute, Kyungpook National University, Daegu 41566, Republic of Korea.
Korean Poultry TS Co., Ltd., Incheon 17415, Republic of Korea.
Poult Sci. 2019 Nov 1;98(11):5892-5899. doi: 10.3382/ps/pez288.
Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) are ubiquitous intestinal bacteria in humans and animals that can easily acquire antimicrobial resistance, which allows them to have roles as antimicrobial resistance indicators. In addition, layer parent stock produces thousands of eggs for the production of commercial laying hens and can transfer a variety of viral and bacterial agents to chicks. The objective of this study was to determine the prevalence and characteristics of antimicrobial-resistant E. faecalis and E. faecium isolated in the layer parent stock level of the egg-layer operating system in South Korea. A total of 129 E. faecalis and 166 E. faecium isolates from 74 flocks of 30 layer parent stock were tested for resistance in this study. The prevalence of doxycycline- (51.9%), erythromycin- (53.5%), high-level gentamicin- (13.2%), high-level kanamycin- (31.0%), high-level streptomycin- (30.2%), and tetracycline- (64.3%) resistant E. faecalis isolates were higher than those for E. faecium isolates (P < 0.05). The ermB gene was detected in 66 (95.7%) erythromycin-resistant E. faecalis isolates, which was higher than that of 32 (71.7%) erythromycin-resistant E. faecium isolates. Twenty-one high-level gentamicin-resistant Enterococcus spp. (17 E. faecalis and 4 E. faecium) carried at least one aminoglycoside-modifying enzyme gene, aac(6')Ie-aph(2')-Ia or ant(6)-Ia. Fourteen isolates that harbored both aac(6')Ie-aph(2')-Ia and ant(6)-Ia exhibited pattern A with IS256 at both ends. Ten high-level ciprofloxacin-resistant Enterococcus spp. (8 E. faecalis and 2 E. faecium) showed amino acid changes from serine to isoleucine at codons 83 in gyrA, and 80 in parC. Also, the virulence genes ace, asa1, efaA, and gelE were detected in this study. To the best of our knowledge, this is the first study to examine the prevalence and characteristics of antimicrobial-resistant E. faecalis and E. faecium isolates in the layer parent stock. Our findings support the need for a surveillance program to monitor the emergence of antimicrobial-resistant E. faecalis and E. faecium in layer operating system.
屎肠球菌（E. faecalis）和粪肠球菌（E. faecium）是人和动物肠道中普遍存在的细菌，它们很容易获得抗药性，因此可以作为抗药性的指标。此外，蛋鸡种鸡生产数千枚鸡蛋用于商业产蛋，并且可以将各种病毒和细菌制剂传递给小鸡。本研究的目的是确定韩国蛋鸡生产系统中蛋鸡种鸡水平分离的耐抗生素屎肠球菌和粪肠球菌的流行率和特征。本研究共检测了 74 个鸡群 30 只蛋鸡种鸡的 129 株屎肠球菌和 166 株粪肠球菌的耐药性。高水平庆大霉素-（13.2%）、高水平卡那霉素-（31.0%）、高水平链霉素-（30.2%）和四环素-（64.3%）耐药屎肠球菌分离株的流行率高于粪肠球菌分离株（P < 0.05）。在 66 株（95.7%）红霉素耐药屎肠球菌分离株中检测到 ermB 基因，高于 32 株（71.7%）红霉素耐药粪肠球菌分离株。21 株高水平庆大霉素耐药肠球菌属（17 株屎肠球菌和 4 株粪肠球菌）携带至少一种氨基糖苷类修饰酶基因 aac(6')Ie-aph(2')-Ia 或 ant(6)-Ia。14 株同时携带 aac(6')Ie-aph(2')-Ia 和 ant(6)-Ia 的分离株在两端均显示出模式 A，带有 IS256。10 株高水平环丙沙星耐药肠球菌属（8 株屎肠球菌和 2 株粪肠球菌）在 gyrA 密码子 83 和 parC 密码子 80 处显示出从丝氨酸到异亮氨酸的氨基酸变化。此外，本研究还检测到了毒力基因 ace、asa1、efaA 和 gelE。据我们所知，这是首次研究蛋鸡生产系统中屎肠球菌和粪肠球菌分离株的耐药性流行率和特征。我们的研究结果支持需要一个监测计划来监测蛋鸡生产系统中屎肠球菌和粪肠球菌的抗药性的出现。
