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Enterohaemorrhagic Escherichia Coli (EHEC) 0157:H7 is exposed to a wide variety of stresses including
gastric acid shock, yet little is known about the impact of stress on EHEC – host cell adhesion. In this
study the attachment to chicken epithelial cells at different pH range, showed that bacteria were able to
attach to intestinal cells in vitro. In addition bacteria subjected to acid shock after growth at an acidic pH
(pre shock-pH 5.0) were found to retain the ability to adhere to chicken epithelial cells, which was absent
in the bacterial cells subjected to acid shock after growth at pH 7. Acid adapted enterohemorrhagic E.
coli could grow well in mucus of streptomycin treated mice after acidic shock, while non- adapted strain
in acid shock was unable to grow in the mucus. Acid adapted, streptomycin resistant strain of EHEC
E.coli was able to colonize and establish infection in the intestine of the streptomycin treated mice 24
hours after oral feeding. The animals were found to excrete E. coli 0157:H7 in their faeces till 2 weeks
period. These data indicate that acid stress of EHEC significantly enhances adhesion to host intestinal
cells both in vitro and in vivo.
Key- Words: Enterohemorrhagic E. Coli, acid stress, intestinal cells.