Presence and characteristics of sorbitol-negative Escherichia coli O157 in healthy sheep faeces

The presence of sorbitol-negative Escherichia coli O157 was investigated in healthy Awassi sheep faeces from 175 randomly selected animals in Burdur province of Turkey. Out of 175 animals, 16 (9.1%) were faecal shedding of sorbitol-negative E. coli O157. Out of the 15 flocks included in the study, 7 (47%) had at least one sheep positive for sorbitol-negative E. coli O157. The isolation rate of sorbitol-negative E. coli O157 ranged from 8.3 to 60% among the animals tested in the flocks. A total of 16 ovine sorbitol-negative E. coli O157 strains were characterized by a multiplex PCR. Results showed that 6 (37.7%) strains carried stx1 gene, 3 (18.8%) stx2 gene and 1 (6.3%) both stx1 and stx2 genes. Intimin (eaeA) gene was detected in 4 (25%) of the strains. None of the strains encoding for stx genes was positive for eaeA gene. The results demonstrate that the majority of sorbitol-negative E. coli O157 strains (62.5%) isolated from Awassi sheep in Burdur province of Turkey are Shiga toxin-producing E. coli that have a potential as human pathogens.