Preventive Veterinary Medicine Department, Faculty of Veterinary, Federal University of Rio Grande Do Sul (UFRGS), Av. Bento Gonçalves, Porto Alegre, Rio Grande do Sul, 9090, 91540-000, Brazil.
Agroindustrial Science and Technology Department, Faculty of Agronomy Eliseu Maciel, Federal University of Pelotas (UFPel), Rio Grande do Sul, Brazil.
Braz J Microbiol. 2022 Dec;53(4):2185-2194. doi: 10.1007/s42770-022-00846-7. Epub 2022 Oct 24.
The aim of this study was to evaluate 140 Salmonella Derby isolates collected over a 10-year period from porcine origins (environment, pig carcass, lymph nodes, intestinal content, and pork) for their phenotypic and genotypic antimicrobial resistance, their ability to produce biofilm, and their genetic relatedness. The minimum inhibitory concentration (MIC) was determined using microdilution broth method and antimicrobial resistance genes were investigated by PCR. The quantification of biofilm formation was performed in sterile polystyrene microtiter plates. Genetic relatedness was determined by Xba-I macrorestriction analysis. The highest frequencies of non-wildtype (nWT) populations were observed against tetracycline (75.7%), streptomycin (70%), and colistin (11.4%), whereas wildtype populations were observed against ciprofloxacin, ceftazidime, and gentamicin. The resistance genes found were bla (ampicillin), aadA variant (streptomycin/spectinomycin), tetA (tetracycline), and floR (florfenicol). On 96-well polystyrene microtiter plate, 68.6% of the isolates proved to be biofilm producers. Among 36 S. Derby isolates selected to PFGE analysis, 22 were clustered with 83.6% of similarity. Additionally, 27 isolates were clustered in 11 pulsotypes, which presented more than one strain with 100% of similarity. Most of S. Derby isolates were able to form biofilm and were classified as nWT or resistant to tetracycline, streptomycin, and colistin. PFGE allowed the identification of closely related S. Derby isolates that circulated in pig slaughterhouses and pork derived products along a decade.
本研究旨在评估 140 株从猪源(环境、猪胴体、淋巴结、肠内容物和猪肉)收集的 10 年来的德比沙门氏菌分离株的表型和基因型抗药性、生物膜形成能力和遗传相关性。采用微量稀释肉汤法测定最小抑菌浓度(MIC),并通过 PCR 检测抗菌药物耐药基因。采用无菌聚苯乙烯微量滴定板定量测定生物膜形成。通过 Xba-I 宏观限制分析确定遗传相关性。观察到非野生型(nWT)群体对抗生素的耐药率最高,分别为四环素(75.7%)、链霉素(70%)和粘菌素(11.4%),而对环丙沙星、头孢他啶和庆大霉素的野生型群体。发现的耐药基因包括 bla(氨苄西林)、aadA 变体(链霉素/大观霉素)、tetA(四环素)和 floR(氟苯尼考)。在 96 孔聚苯乙烯微量滴定板上,68.6%的分离株被证明是生物膜生产者。在选择进行 PFGE 分析的 36 株德比沙门氏菌分离株中,22 株与 83.6%的相似度聚类。此外,27 株分离株聚类为 11 个脉冲型,其中有 100%相似度的菌株超过 1 株。大多数德比沙门氏菌分离株能够形成生物膜,并被归类为 nWT 或对四环素、链霉素和粘菌素耐药。PFGE 能够识别在猪屠宰场和猪肉制品中循环的密切相关的德比沙门氏菌分离株,这一情况在十年间持续存在。