江苏省东台地区家畜非O157产志贺毒素大肠埃希菌耐药性及多位点序列分型分析

韩悦; 韩影; 刘敏琪; 董晨; 金辉

doi:10.3784/jbjc.202112060625

江苏省东台地区家畜非O157产志贺毒素大肠埃希菌耐药性及多位点序列分型分析

Antibiotic resistance and multi-locus sequence typing of non-O157 Shiga toxin-producing Escherichia coli from livestock in Dongtai, Jiangsu

摘要

摘要:
目的了解江苏省东台地区家畜来源非O157产志贺毒素大肠埃希菌（STEC）抗生素耐药表型、耐药基因，以及多位点序列分型（MLST）情况。
方法于2019年5月，江苏省东台市采集家畜粪便样本301份（羊粪便231份，牛粪便70份），分离非O157 STEC菌株。采用改良微量肉汤法测定菌株对21种抗生素最小抑菌浓度（MIC）；通过全基因组测序技术对O∶H血清型、耐药基因和多位点序列型别进行预测。
结果在68株非O157 STEC中，有32株对至少1种药物耐药。其中，STEC对四环素耐药率最高（42.6%），其次分别对阿奇霉素（36.8%）、复方新诺明（35.3%）、链霉素（32.3%）、氯霉素（30.9%）、环丙沙星（29.4%）等9种抗生素耐药；共识别出25种耐药基因，其中，氨基糖苷类耐药基因和叶酸途径抑制剂类耐药基因携带率最高（44.1%），其次为四环素类耐药基因tet(A)（42.6%）；MLST将分离株分为13种ST型，其中ST43（19.1%）和ST155（16.2%）比例较高。最小生成树显示，具有相同血清型的STEC菌株多聚集在一起。 STEC中4种ST型别（ST25、ST40、ST43、ST675）分别与引起肠溶血性尿毒综合征相关的肠出血性大肠埃希菌（HUSEC）聚类成簇。
结论江苏东台地区家畜中非O157 STEC耐药形势复杂，且存在多重耐药现象。此外，该地区STEC菌株对人群存在潜在威胁，家畜作为非O157 STEC宿主应引起重视。

Abstract:
Objective To investigate and characterize the antibiotic resistance, antibiotic resistance genes, and multi-locus sequence typing (MLST) of non-O157 Shiga toxin-producing Escherichia coli (STEC) isolated from livestock in Jiangsu.
Methods In May 2019, a total of 301 stool samples, including 231 sheep stool samples and 70 cattle stool samples, were collected in Dongtai of Jiangsu province for the isolation of non-O157 STEC. The modified micro broth method was used to determine the minimum inhibitory concentration (MIC) of 21 antibiotics to the isolates. The serotypes, antibiotic resistance genes and MLST of the isolates were analyzed by whole-genome sequencing (WGS).
Results The drug sensitivity test showed that of the 68 non 157-STEC strains, 32 were at least resistant to one antibiotic. It was found that STEC showed the highest resistance rate to tetracycline (42.6%), followed by azithromycin (36.8%), trimethoprim-sulfamethoxazole (TMP/SMX) (35.3%), streptomycin (32.3%), chloramphenicol (30.9%) and ciprofloxacin (29.4%). A total of 25 AMR genes were identified. The majority of STEC isolates carried the antibiotic resistance genes associated with aminoglycoside (44.1%), TMP/SMX (44.1%), and tetracycline (42.6%). MLST showed that the isolates were divided into 13 sequence types (STs), among which ST43 (19.1%) and ST155 (16.2%) had higher proportions. The minimum spanning tree (MST) indicated that most STEC strains with the same serotypes were clustered together. Four STs of STEC strains, including ST25, ST40, ST43 and ST675, were clustered with HUSEC strains.
Conclusion The antibiotic resistance of non-O157 STEC in livestock is complex, and there are multi-drug resistant strains. In addition, STEC strains in this area pose a potential threat to the population, and close attention needs to be paid to livestock, as an important host of non-O157 STEC.

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