Gozi Katia Suemi, Froes Juliana Rodrigues, Deus Ajude Luana Perpetua Tobias, da Silva Caroline Rodrigues, Baptista Rafaela Speranza, Peiró Juliana Regina, Marinho Marcia, Mendes Luiz Claudio Nogueira, Nogueira Mara Corrêa Lelles, Casella Tiago
Centro de Investigação e Microrganismos, FAMERP, São José do Rio Preto, Brazil.
Faculdade de Medicina Veterinária, São Paulo State University (UNESP), Araçatuba, Brazil.
Front Microbiol. 2019 Jun 25;10:1394. doi: 10.3389/fmicb.2019.01394. eCollection 2019.
Antimicrobial resistance (AR) is a public health issue since it limits the choices to treat infections by in humans and animals. In Brazil, the ovine meat market has grown in recent years, but studies about AR in sheep are still scarce. Thus, this study aims to investigate the presence of AR in isolated from lambs during feedlot. To this end, feces from 112 lambs with 2 months of age, after weaning, were collected on the first day of the animals in the feedlot (day 0), and on the last day before slaughtering (day 42). Isolates were selected in MacConkey agar supplemented with 4 mg/L of ceftiofur and identified by biochemical methods. Isolates were submitted to an antimicrobial susceptibility test by disc-diffusion and PCR to investigate genes for phylogenetic group, virulence determinants and resistance to the several antimicrobial classes tested. The genetic localization of the genes detected was elucidated by S1-PFGE followed by Southern blot-hybridizations. The isolates were typed by -PFGE and MLST methods. Seventy-eight were isolated from 8/112 (7.1%) animals on day 0, and from 55/112 (49.1%) animals on day 42. Since only was present in almost all (97.4%) as a virulence gene, and also 88.5% belonged to phylogroups B1 or A, we consider that isolates represent intestinal commensal bacteria. The dendrogram separated the 78 non-virulent isolates in seven clusters, two of which comprised 50 belonging to ST/CC 1727/446 or ST 3994 recovered on day 42 commonly harboring the genotype - -----. Special attention should be given to the presence of , a worldwide gene spread, and , a hitherto undetected gene in from food-producing animals in Brazil. Importantly, lineages and plasmids carrying genes detected here have already been reported as sources of infection in humans either from animals, food, or the environment, which raises public health concerns. Hence, two types of commensal carrying important AR genes clearly prevailed during feedlot, but lambs are also reservoirs of bacteria carrying important AR genes such as and , mostly related to antimicrobial treatment failure.
抗菌药物耐药性（AR）是一个公共卫生问题，因为它限制了人类和动物感染治疗的选择。在巴西，近年来羊肉市场有所增长，但关于绵羊抗菌药物耐药性的研究仍然很少。因此，本研究旨在调查育肥期羔羊分离出的大肠杆菌中抗菌药物耐药性的存在情况。为此，在育肥期第1天（第0天）和屠宰前最后一天（第42天）收集了112只2月龄断奶羔羊的粪便。在添加4mg/L头孢噻呋的麦康凯琼脂中选择分离株，并通过生化方法进行鉴定。通过纸片扩散法和PCR对分离株进行抗菌药物敏感性试验，以研究系统发育群、毒力决定因素和对几种测试抗菌药物类别的耐药性基因。通过S1-PFGE随后进行Southern杂交来阐明检测到的大肠杆菌基因的基因定位。通过脉冲场凝胶电泳（PFGE）和多位点序列分型（MLST）方法对分离株进行分型。在第0天，从8/112（7.1%）只动物中分离出78株大肠杆菌，在第42天，从55/112（49.1%）只动物中分离出。由于几乎所有分离株（97.4%）中都存在stx作为毒力基因，并且88.5%属于B1或A系统发育群，我们认为分离株代表肠道共生细菌。聚类图将78株无毒力分离株分为7个簇，其中两个簇包含50株，属于第42天回收的ST/CC 1727/446或ST 3994，通常携带基因型------。应特别关注stx的存在，这是一种在全球传播的基因，以及tet(A)，这是巴西产肉动物大肠杆菌中迄今未检测到的基因。重要的是，这里检测到的携带耐药基因的大肠杆菌谱系和质粒已被报道为人类动物源性、食物源性或环境源性感染的来源，这引发了公共卫生问题。因此，两种携带重要耐药基因的共生大肠杆菌在育肥期明显占优势，但羔羊也是携带重要耐药基因如bla CTX-M-1和tet(A)的细菌的储存宿主，这些基因大多与抗菌治疗失败有关。
