in Shiga toxin-producing Escherichia coli (STEC) isolates from cattle and sheep feces in the Southeastern region of the State of Goiás, Brazil. Pesquisa Veterinária Brasileira 41:e06747, 2021. Graduate Program in Animal Bioscience, Universidade Federal de Jataí,

RESUMO. [Subtipagem de Stx1 e Stx2 e resistência antimicrobiana em isolados de Escherichia coli produtoras de toxina Shiga (STEC) de fezes de bovinos e ovinos na região sudeste de Goiás, Brasil. ] O presente estudo teve como objetivo subtipar os genes Stx1 e Stx2 e caracterizar a resistência antimicrobiana em 106 isolados de Escherichia coli produtoras de toxinas Shiga (STEC) isoladas de fezes de bovinos e ovinos. A PCR foi utilizada para determinar os subtipos e o método de difusão em disco foi utilizado para avaliar a resistência antimicrobiana. Dez antibióticos de cinco classes diferentes foram testados. Entre os isolados de origem bovina, foram identificados dois subtipos de Stx1 (Stx1a e Stx1c) e quatro subtipos de Stx2 (Stx2a, Stx2b, Stx2c e Stx2d). Nos isolados de origem ovina, foram identificados dois subtipos de Stx1 (Stx1a e Stx1c) e quatro subtipos de Stx2 (Stx2a, Stx2b, Stx2c e Stx2g). Os resultados obtidos sugerem ABSTRACT.Arrais B.R. , Silveira A.V. B.A., Oliveira A.F. , Barbosa N.C. , Stella A.E. , Alves B.G. , Ferreira M.R. A. & Moreira C.N. 2021. Stx1 and Stx2 subtyping and antimicrobial resistance in Shiga toxin-producing Escherichia coli (STEC) isolates from cattle and sheep feces in the Southeastern region of the State of Goiás, Brazil. Pesquisa Veterinária Brasileira 41:e06747, 2021. Graduate Program in Animal Bioscience, Universidade Federal de Jataí, Campus Jatobá, BR-364 Km 195 3800, Cidade Universitária, Jataí, GO 75801-615, Brazil. E-mail: marcosferreiravet@gmail.com The present study was aimed at subtyping of Stx1 and Stx2 genes and characterization of antimicrobial resistance in 106 Shiga toxin-producing Escherichia coli (STEC) strains isolated from cattle and sheep feces. PCR was used to determine the subtypes, and the disk-diffusion method was used to evaluate the antimicrobial resistance. Ten antibiotics from five different classes were tested. Among the isolates of bovine origin, two subtypes of Stx1 (Stx1a and Stx1c), and four subtypes of Stx2 (Stx2a, Stx2b, Stx2c, and Stx2d) were identified. In isolates of sheep origin, two subtypes of Stx1 (Stx1a and Stx1c), and four subtypes of Stx2 (Stx2a, Stx2b, Stx2c, and Stx2 g) were identified. The results obtained suggest the presence of high diversity in Stx1 and Stx2 genes. Further, 96.6% (57/59) of bovine fecal strains and 89.4% (42/47) of sheep fecal strains showed resistance to at least one tested antibiotic. In both animal species, most strains were multidrug-resistant (MDR) (67.8% in cattle and 59.6% in sheep), with no significant difference between host animals. Adult animals were eight times more likely to have STEC with greater pathogenic potential. STEC with the highest pathogenic potential were three times more likely to be multidrug-resistant than STEC with the lowest pathogenic potential. The data reported in this study suggests the occurrence of strains with high potential pathogenicity in the region studied. Therefore, the ruminants of this region are carriers of strains that can cause infections in humans.