AUTHOR=Baldo Valentina , Salogni Cristian , Giovannini Stefano , D'Incau Mario , Boniotti Maria Beatrice , Birbes Laura , Pitozzi Alessandra , Formenti Nicoletta , Grassi Andrea , Pasquali Paolo , Alborali Giovanni Loris 

TITLE=Pathogenicity of Shiga Toxin Type 2e Escherichia coli in Pig Colibacillosis

JOURNAL=Frontiers in Veterinary Science

VOLUME=Volume 7 - 2020

YEAR=2020

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2020.545818

DOI=10.3389/fvets.2020.545818

ISSN=2297-1769

ABSTRACT=Shiga toxin type 2e (Stx2e) Escherichia coli is the causative factor of diarrhea and edema in swine. The aims of this study were to determine the prevalence of Stx2e-producing E. coli isolates and to characterize isolates from clinical cases of pig colibacillosis and healthy swine. During the 11 years of the study (2006 – 2017), a total of 233 Stx2e-producing isolates were detected – 230 out of 2060 (11.16%) E. coli isolated from diseased pigs and 3 out of 171 (1.75%) from healthy swine. Stx2e-producing isolates were indeed more present in clinical colibacillosis cases than in healthy pigs (p = 0.0002). The predominant serogroup was O139 (79.82%) and the most common fimbrial factor present in these isolates was F18 (177 isolates), followed by F6 (5 isolates). The enterotoxins LTI, STa, and STb were detected in 10.43%, 41.73%, and 48.26% of the isolates, respectively. The predominant virotypes F18-Stx2e and F18-STa-STb-Stx2e were similarly present in weaners (33.33% and 35.52%) and finishers (38.30% and 25.53%). Among isolates from diseased pigs, O139 and F18 were the more frequently identified serogroup and virulence factor, respectively. Of the tested 230 Stx2e-producing isolates isolated from diseased pigs, 29 (12.60%) harboured genes encoding ESBL, particularly TEM (79.30%), CTX-M1 (17.20%), and CMY-2 (3.40%). Antimicrobial resistance to tetracycline was the most common characteristic (98.25%), followed by ampicillin (93.91%), cephalotin (90.43%) and trimethoprim/sulfamethoxazole (82.17%). Our results showed that Stx2e-producing E. coli were more frequently associated with clinical forms of colibacillosis, with minimal probability to isolate these isolates from healthy pigs.