Abstract
Escherichia coli O157:H7 is a predominant serotype of Shiga toxin producing E. coli (STEC) and is responsible for many outbreaks worldwide. Until recently, there is no comparative study on the bovine and clinical isolates as no STEC O157:H7 has been isolated from patients in Bangladesh. In the present study, the local bovine isolates were compared with a reference clinical strain to investigate whether the bovine isolates are capable of producing same degree of illness as the clinical strain. Two local isolates (CD-11 and CD-17) of bovine origin and a reference clinical strain (E. coli O157:H7 NCTC 12079) were investigated for the presence of virulence genes by polymerase chain reaction (PCR), Shiga toxin production by VTEC-RPLA, invasive property by Congo red binding and Sereny’s keratoconjunctivitis, and other enterotoxic, cytotoxic and mouse lethal activities. Both the local isolates and the reference clinical strain showed the presence of eae and stx2 genes and were found to be non-invasive. The isolates also produced enterotoxin, cytotoxin and mouse lethality similar to that found with the reference strain. All these results strongly suggest that the local bovine STEC O157:H7 isolates have potential to cause diseases similar to clinical STEC O157:H7 strain, which might lead to any outbreak in Bangladesh. Key words: Bovine, Escherichia coli, STEC O157:H7, Bangladesh.
Highlights
The bacterium Escherichia coli O157:H7 has been reported as the predominant serotype of Shiga toxin producing E. coli (STEC) (Armstrong et al, 1996; Besser et al, 1999; Tarr et al, 2005)
A study on cattle and human clinical isolates of STEC O157 showed that cattle isolates possessed all the virulence traits that are typical for the human pathogenic strains
In another study in Czech Republic, it was reported that the phenotypic and genotypic characteristics of both bovine and human STEC O157 isolates were identical or closely related which supported the pathogenic potential of the bovine isolate for humans (Bielaszewska et al, 2000)
Summary
The bacterium Escherichia coli O157:H7 has been reported as the predominant serotype of Shiga toxin producing E. coli (STEC) (Armstrong et al, 1996; Besser et al, 1999; Tarr et al, 2005). 20 μL of an overnight culture of the STEC O157:H7 strains (both bovine isolates and reference clinical) or Shigella flexneri 2a containing approximately 5 x 108 cells/ml in phosphate buffer saline (PBS) was inoculated into one of the eyes of a guinea pig and the other eye served as the negative control.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
