Department of Nutritional Sciences, College of Family and Consumer Sciences, University of Georgia, Athens, GA, USA.
Department of Crop and Soil Sciences, College of Agriculture, University of Georgia, Athens, GA, USA.
J Food Prot. 2023 Aug;86(8):100113. doi: 10.1016/j.jfp.2023.100113. Epub 2023 Jun 7.
Antimicrobials and heavy metals are commonly used in the animal feed industry. The role of in-feed antimicrobials on the evolution and persistence of resistance in enteric bacteria is not well described. Whole-Genome Sequencing (WGS) is widely used for genetic characterizations of bacterial isolates, including antimicrobial resistance, heavy metal tolerance, virulence factors, and relatedness to other sequenced isolates. The goals of this study were to i) use WGS to characterize Salmonella enterica (n = 33) and Escherichia coli (n = 30) isolated from swine feed and feed mill environments; and ii) investigate their genotypic and phenotypic antimicrobial and heavy metal tolerance. Salmonella isolates belonged to 10 serovars, the most common being Cubana, Senftenberg, and Tennessee. E. coli isolates were grouped into 22 O groups. Phenotypic resistance to at least one antimicrobial was observed in 19 Salmonella (57.6%) and 17 E. coli (56.7%) isolates, whereas multidrug resistance (resistant to ≥3 antimicrobial classes) was observed in four Salmonella (12%) and two E. coli (7%) isolates. Antimicrobial resistance genes were identified in 17 Salmonella (51%) and 29 E. coli (97%), with 11 and 29 isolates possessing genes conferring resistance to multiple antimicrobial classes. Phenotypically, 53% Salmonella and 58% E. coli presented resistance to copper and arsenic. All isolates that possessed the copper resistance operon were resistant to the highest concentration tested (40 mM). Heavy metal tolerance genes to copper and silver were present in 26 Salmonella isolates. Our study showed a strong agreement between predicted and measured resistances when comparing genotypic and phenotypic data for antimicrobial resistance, with an overall concordance of 99% and 98.3% for Salmonella and E. coli, respectively.
抗菌药物和重金属通常用于动物饲料行业。饲料中使用抗菌药物对肠道细菌耐药性的演变和持续存在的影响尚未得到充分描述。全基因组测序（WGS）广泛用于细菌分离物的遗传特征分析，包括抗菌药物耐药性、重金属耐受性、毒力因子以及与其他已测序分离物的相关性。本研究的目的是：i）使用 WGS 对来自猪饲料和饲料厂环境的沙门氏菌（n=33）和大肠杆菌（n=30）进行分离物的遗传特征分析；ii）研究它们的基因型和表型的抗菌药物和重金属耐药性。沙门氏菌分离株属于 10 个血清型，最常见的血清型为古巴、森滕贝格和田纳西。大肠杆菌分离株分为 22 个 O 群。19 株沙门氏菌（57.6%）和 17 株大肠杆菌（56.7%）分离株对至少一种抗菌药物表现出耐药性，而 4 株沙门氏菌（12%）和 2 株大肠杆菌（7%）分离株表现出多药耐药性（对≥3 种抗菌药物类别耐药）。在 17 株沙门氏菌（51%）和 29 株大肠杆菌（97%）中鉴定出抗菌药物耐药基因，其中 11 株和 29 株分离株携带赋予多种抗菌药物类别的耐药性的基因。表型上，53%的沙门氏菌和 58%的大肠杆菌对铜和砷表现出耐药性。所有携带铜耐药操纵子的分离株均对测试的最高浓度（40mM）表现出耐药性。26 株沙门氏菌分离株携带铜和银的重金属耐受基因。当比较抗菌药物耐药性的基因型和表型数据时，本研究显示出预测和测量的耐药性之间具有很强的一致性，沙门氏菌和大肠杆菌的总体一致性分别为 99%和 98.3%。
