奶牛牧场养殖环境中产ESBL耐药菌的流行特征

Epidemiological Characteristics of ESBL-Producing Resistant Bacteria in Dairy Farming Environment

本研究旨在探索奶牛养殖环境中产超广谱β-内酰胺酶(extended-spectrum beta-lactamases,ESBL)耐药菌的流行特征。2020-2021年,采集6个内蒙古和宁夏牧场共160份牛奶、乳区皮肤拭子和环境来源的多种类型样本,分别进行了β-内酰胺酶检测、产ESBL耐药菌的分离鉴定、药敏试验以及菌株的全基因组测序。结果显示:24份奶样的检测结果显示,各牧场β-内酰胺酶阳性率为75%~100%。其中,5个牧场的153份样本共分离出6种产ESBL耐药菌,这些产ESBL耐药菌对阿莫西林(100%)、头孢噻肟(91.0%)和头孢他啶(78.2%)均具有较高耐药率;全基因组显示,14株产ESBL大肠杆菌携带多种耐药基因,以bla_(CTX-M)(100%)携带率最高。通过对内酰胺酶阳性奶样进行分析,发现造成牧场奶样β-内酰胺酶阳性的主要菌株是产ESBL鲍曼不动杆菌,并且该耐药菌携带有bla_(CTX-M)、bla_(TEM)、bla_(OXA)型β-内酰胺类耐药基因。本研究明确了内蒙古和宁夏牧场养殖环境中产ESBL耐药菌的流行特征,并对造成内蒙古1个牧场牛奶内酰胺酶阳性原因进行了追溯研究。

The purpose of this study was to explore the epidemiological characteristics of ESBL-producing resistant bacteria in the dairy farming environments.A total of 160 samples were collected from 6 farms in Inner Mongolia and Ningxia from 2020 to 2021,including milk,milk area skin swabs and environmental sources.β-lactamase rapid test strip,with the isolation and identification,drug sensitivity,and genome sequencing of ESBL-producing resistant bacteria,were conducted respectively.The positive rate of β-lactamase in all farms was 75%-100% in 24 milk samples.A total of 6 ESBL-producing resistant strains were isolated from 153 samples in 5 farms,and these ESBL-producing resistant strains had high resistance rates to amoxicillin(100%),cefotaxime(91.0%) and ceftazidime(78.2%).And 14 ESBL-producing Escherichia coli strains sequenced were found to carry multiple drug resistance gene types,with bla_(CTX-M)(100%) carrying rate being the highest.At the same time,the sixth special farm with “long-term positive lactamase test” was found that ESBL-producing Acinetobacter baumannii was the main strain of β-lactamase positive in the milk of the farm,and the resistant strain carried bla_(CTX-M),bla_(TEM) and bla_(OXA) β-lactamase resistance genes.This study identified the epidemiological characteristics of ESBL-producing resistant bacteria in farm environments in Inner Mongolia and Ningxia,and the causes of lactamase positivity in the milk of one farm in Inner Mongolia were successfully traced back.