科研之友
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摘要
This study was carried out to determine the prevalence of E. coli O157: H7 in mastitic bovine milk, to investigate the major virulence genes [shiga toxins (stx1 and stx2), intimin (eae), enterohaemolysin (ehlyA), and traslocated intimin receptor (tir)], antibiotic resistance profiles and clonality of the isolates. A total of 484 bovine mastitic milk samples collected from dairy farms in Aydin is a county situated by Aegean Sea at the west part of Turkey. The serotype of the isolates was confirmed by the presence of specific genes using polymerase chain reaction (PCR). Presence of virulence genes was also tested by PCR. Resistance to 13 antimicrobial agents was investigated by the disk diffusion method. The clonality was determined by enterobacterial repetitive intergenic consensus (ERIC) PCR. From 484 bovine milk with mastitis a total of 8 (1.65%) E. coli O157: H7 was isolated from 5 farms. Among virulence genes tested, ehlyA was positive for all 8 (100.0%) isolates, 7 isolates carried (87.5%) eae, tir and stx2 genes. Isolates were all susceptible to the antimicrobials tested except to tetracycline for two (25.0%) and to streptomycin for one (12.5%). The clonal spread was detected among the animals with mastitis by ERIC PCR. Among 8 strains tested, a total of 6 profiles were detected. There were two couples of "identical" isolates. The four isolates from the same farm appeared to be closely related, and distantly related to the isolates from other farms. Presence of E. coli O157: H7 strains in mastitic bovine milks may cause public health problems. We suggest that there is a need for improving the hygienic conditions of the farms which may help reduce transmission of E. coli O157: H7 to humans.
- 出版日期2017-3
