Isolation and characterization Shiga toxin-producing Escherichia coli from sheep and goats in Jordan with evidence of multiresistant serotype O157:H7

Ninety-three rectal swabs of lambs and young goats from two extensively and two intensively managed herds in Jordan were taken and examined for Shiga toxin-producing Escherichia coli (STEC). The bacteriological examination included the preenrichment of rectal swabs in EC broth with novobiocin, and a subsequent parallel isolation on enterohemolysin agar and immunomagnetic separation with cultivation on CT-SMAC. The STEC O157:H7 strains were demonstrated in 8 of 32 diarrheic lambs 1to 3-weeks old in one sheep herd with intensive milk production. In the remaining three herds, serogroups O128, O78, O15 and serotype O128:K85 of STEC strains were the most frequent findings. The presence of stx2, ehlyA and eaeA genes in all STEC O157:H7 isolates was confirmed by PCR. In two untypable STEC isolates, stx2 and ehlyA genes were detected. In other STEC non-O157 isolates, only stx1 a ehlyA genes were found. All STEC O157:H7 isolates were resistant against sulphonamides and chloramphenicol, five were also resistant against ampicillin and streptomycin, one against co-trimoxazole. One isolate was resistant against ampicillin, ampicillin-sulbactam, cephalosporins (cefazolin, cefuroxime), monobactams (aztreonam), sulphonamides, co-trimoxazole, aminoglycosides, tetracycline and chloramphenicol. Compared the resistant STEC O157:H7 isolates, the multiresistant isolate had a different RAPD pattern. Of 36 STEC non-O157 isolates, one isolate was resistant against sulphonamides and co-trimoxazole, and another one against ampicillin, streptomycin, sulphonamides and co-trimoxazole. STEC isolates resistant against antimicrobial agents were demonstrated only in herds with intensive management.