Are Non-O157 Shiga Toxin-producing Escherichia coli Imposing Their Predominance Over O157 in Farm Animals and Human?

摘要

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen that causes diarrheal diseasein humans which may progress to serious complications and death. The aim of this study was to investigatethe occurrences of STEC in farm animals and human in Egypt. A total of 461 faecal samples were collected frombuffalo, dairy cattle, feedlot (beef) cattle, sheep and goats as 40, 86, 67, 192 and 76 samples, respectively.Additionally, 93 stool samples were obtained from human, living in urban (42 samples) and rural (51 samples)areas and all had gastro-intestinal complaints. Samples were screened withenzyme-linked immunosorbent assayto detect shiga toxins (stx) and then positive samples were cultured onto selective chromogenic media for STEC.Afterwards, positive isolates were subjected to biochemical tests to be proved as E. coli and confirmedmolecularly by the polymerase chain reaction for the presence of stx-encoding genes. The occurrence of STECin faeces of animals were 45.0%, 26.7%, 4.5%, 2.6% and 2.6% for buffalos, dairy cattle, feedlot (beef) cattle,sheep and goats, respectively, with 11.1% as an overall occurrencerate of STEC in sampled animals. No STECwas detected in stool samples of human living in urban areas, while 5samples from those living in rural areastested positive for the presence of STEC. The overall occurrence rate of STEC in human samples was 5.4%. Itis noteworthy that all of the obtained STEC isolates, according to O157 latex agglutination test, proved to benon-O157 STEC. This study demonstrated the predominance of non-O157 STEC, highlighted the role of buffaloas an overlooked reservoir for STEC and showed the higher risk of STEC infection to human in rural areas.