Detection of high-risk Avian Pathogenic Escherichia coli (APEC) isolated from broilers in São Paulo, Brazil

Some high-risk Avian Pathogenic Escherichia coli (APEC) clones have been associated with increased economic losses caused by avian colibacillosis. They may represent an additional food consumption concern due to the potential zoonotic role causing urinary tract infections mainly related to E. coli ST73 and ST95 lineages. This study aimed to characterize APEC isolated from slaughterhouse carcasses presenting lesions compatible with avian colibacillosis. We analyzed about 6500 broilers carcasses, and 48 showed lesions consistent with colibacillosis. Forty-four strains of E. coli were isolated, with 77.27% (n = 34/44) classified as APEC. The isolates belonged to the phylogenetic groups B2 (41.17%, n = 14/34), G (20.59%, n = 7/34), A (17.65%, n = 6/34), B1 (8.82%, n = 3/34), and E (5.88%, n = 2/34). Determining the phylogenetic group of 5.88% (n = 2/34) of the strains was impossible. Moreover, 20.59% (n = 7/34) were positive to the clonal groups ST117, 8.82% (n = 3/34) to ST95, and 8.82% (n = 3/34) were classified as belonging to serogroup O78 by PCR screening. Strains of APEC from O78 serogroup and ST117 are considered high-risk clones for poultry, and our data reinforced the need for surveillance of these pathogens in poultry farms and slaughterhouses.