Enterobacteriaceae in calves, cows and milking environment may act as reservoirs of virulence and antimicrobial resistance genes

Abstract The aim of this study was to investigate the presence of virulence and antimicrobial resistance genes and clonal profile of Enterobacteriaceae isolated from calves, cows, feeding buckets and the milk bucket. A a total of 31 Enterobacteriaceae isolates from calves (6), milk bucket (6), feeding buckets (6) and from cows’ rectum (13) were used. The presence of LT, STa, STb, STx1, STx2, eae, rmpA, wabG, mrkD, kfu, mcgA, fimH and uge as well as the antimicrobial resistance genes: AmpC MOX, FOX, MIR, ACT, DHA, ACC, CTX-M-1, CTX-M2, TEM KPC and MCR-1 and SH were evaluated by PCR. The LT toxin gene were detected in five isolates (16.1%) and the mrkD gene was detected in three isolates (9.0%). The CTX-M-1 gene was detected in 13 isolates (41.9%), CTX-M-2 in five isolates (16.1%) and ACC-M in four isolates (12.9%). Most of the isolates obtained demonstrated, resistance to cephalothin (87.5%), ampicillin, (87.5%) and streptomycin (84.3%) with multidrug resistance observed in all isolates. Isolates from bucket and cow’s rectum, calves and milk bucket, calf and cow’s rectum shared the same pulsotypes. These findings may suggest that enterobacteria carring virulence and resistance genes may persist in the environment and became a reservoir of these genes.

摘要 本研究旨在调查从犊牛、成年母牛、饲喂桶及奶桶中分离的肠杆菌科（Enterobacteriaceae）细菌的毒力基因、抗菌药物耐药基因分布及其克隆谱系特征。本研究共纳入31株肠杆菌科分离株，其中犊牛来源6株、奶桶来源6株、饲喂桶来源6株、母牛直肠来源13株。采用聚合酶链式反应（Polymerase Chain Reaction，PCR）检测了LT、STa、STb、STx1、STx2、eae、rmpA、wabG、mrkD、kfu、mcgA、fimH及uge等毒力基因，以及AmpC MOX、FOX、MIR、ACT、DHA、ACC、CTX-M-1、CTX-M-2、TEM、KPC、MCR-1及SH等抗菌药物耐药基因。结果显示，5株分离株（16.1%）携带LT毒素基因，3株分离株（9.0%）携带mrkD基因；13株分离株（41.9%）携带CTX-M-1基因，5株（16.1%）携带CTX-M-2基因，4株（12.9%）携带ACC-M基因。多数分离株对头孢噻吩（87.5%）、氨苄西林（87.5%）及链霉素（84.3%）耐药，所有分离株均呈现多重耐药性。来自饲喂桶与母牛直肠、犊牛与奶桶、犊牛与母牛直肠的分离株具有相同的脉冲型（pulsotype）。本研究结果提示，携带毒力与耐药基因的肠杆菌科细菌可在环境中持续存在，并成为此类基因的储存库。