Background: Urinary tract infections (UTI) cause severe losses to the swine industry worldwide and uropathogenic Escherichia coli (UPEC) are the main agent isolated from UTI in sows.

Objective: The aim of this study was to investigate the virulence genes, assess the phylogenetic background, clonal diversity, and the pattern of resistance to antimicrobials in 186 isolates of UPEC isolated from sows in Brazil.

Materials and methods: Urine samples from 300 sows of three herds with clinical signs from São Paulo State (Brazil) were screened for UTI; samples with suggestive results were submitted to bacterial isolation. E. coli strains isolated were characterized using disk diffusion technique, polymerase chain reaction and Single-enzyme amplification fragment length polymorphism (SE-AFLP).

Results: Virulence genes focH and papC were present in 78.5% and 58% of strains, respectively, followed by cnf1 (23.2%), afa (13.4%), sfa (11.3%), iucD (6.9%), and hlyA (1.6%). No clonal relatedness was found by SE-AFLP. A total of 98% of isolates (182/186) were multidrug resistant, and the highest levels of resistance were to sulfonamides, tetracycline, florfenicol, and ampicillin. Isolates were classified in phylogenetic group B1 (34.4%), followed by D (33.9%), E (30.1%) and A (1.6%).

Conclusions: The data obtained suggest that pigs from clinically affected herds may serve as a reservoir of uropathogenic and multidrug-resistant E. coli strains.

背景：泌尿道感染（UTI）给全世界的养猪业造成严重损失，泌尿道致病性大肠杆菌（UPEC）是从母猪的UTI中分离出来的主要病原体。

目的：本研究的目的是调查巴西母猪的UPEC 186株分离株的毒力基因，评估系统发育背景，克隆多样性以及对抗菌素的耐药模式。

材料和方法：从巴西圣保罗州（巴西）的三只具有临床体征的牛群的300头母猪的尿液样本中筛选出尿路感染。结果提示的样品将进行细菌分离。使用圆盘扩散技术，聚合酶链反应和单酶扩增片段长度多态性（SE-AFLP）对分离的大肠杆菌进行表征。

结果：毒力基因FOC H和PAP C组存在于78.5％和菌株的58％，分别随后CNF 1（23.2％），AFA（13.4％），SFA（11.3％），IUC d（6.9％），和Hly A（1.6％）。SE-AFLP未发现克隆相关性。共有98％的分离株（182/186）具有多药耐药性，对磺酰胺，四环素，氟苯尼考和氨苄青霉素的耐药率最高。分离株被分类为系统发育组B1（34.4％），其次是D（33.9％），E（30.1％）和A（1.6％）。

结论：获得的数据表明，受临床影响的牛群的猪可作为尿毒症和多药耐药大肠杆菌菌株的贮藏库。