Molecular characterization of pathogenic Escherichia coli isolated from diarrheic and in-contact cattle and buffalo calves

AbstractEscherichia coli field isolates from calves were characterized and categorized into the most significant diarrheagenic pathotypes using polymerase chain reaction (PCR) assays with different specific primers. The used PCR systems were designed to detect sequences representing the group-specific virulence genes encoding fimbriaef5 (K99), Shiga toxins (stx1 andstx2), heat-stable enterotoxins (st), heat-labile enterotoxins (lt), intimin (eae), hemolysin (hylA), and EAEC heat-stable enterotoxin (astA). In the present work, a total of 150E. coli field isolates were recovered from 150 fecal swabs collected from 100 diarrheic and 50 apparently healthy in-contact cattle and buffalo calves under 3  months old. Out of these 150 isolatedE. coli, 106 isolates from 77 diarrheic and 29 in-contact calves harbored one or more of the investigated virulence genes. The pathotyping of the isolates could classify them into shigatoxigenicE. coli (STEC), enteropathogenicE. coli (EPEC), enterotoxigenicE. coli (ETEC), and enteroaggregativeE. coli (EAEC) with a 30.7, 2.7, 12.7, and 7.3% distribution, respectively. Meanwhile, the detection rates off5,stx1,stx2,st,lt,eae,hylA, andastA genes were 17.3, 27.3, 6.7, 10, 37.3, 17.7, 9.3, and 20.7%, respectively. These virulence genes were found either single or in different combinations, such asstx/eae,stx/st/f5,eae/st/f5, orst/lt/f5. Four attaching-effacing shigatoxigenicE. coli isolates (AE-STEC) harboringstx/eae were retrieved from diarrheic calve...
Source: Tropical Animal Health and Production - Category: Veterinary Research Source Type: research