Although
E. coli O157 is responsible for toxin, but some other virulence-associated
factor conveyed by STEC is a protein called intimin which is necessary for adherence
of STEC to the intestinal epithelial cells, causing attaching and effacing (AE)
lesions in the intestinal mucous membrane.The chromosomal gene eae, named intimin which is factor of a
pathogenicity island termed the locus for enterocyte effacement
(LEE).Enterohaemolysin (Ehly), is a component
that may also affect the virulence of STEC are also known as enterohaemorrhagic E. coli hemolysis (EHEC-HlyA) , which is encoded by ehxA gene (Goldwater, P.N., Bettelheim,
K.A.1995).E. coli O157:H7 comes out
to be the predominant serotype found linked with foodborne infections, E. coli O157:H- isolates may also bear
these virulence markers and cause disease in humans (Schmidt,H., Biutin, L.,
Karch, H.1995).Six E. coli virulence genes were characterized by
multiplex PCR including;heat-labile enterotoxin (LT; 30%),heat-stable
enterotoxins (STa; 33.3%), two Shiga toxins: (Stx1; 86.67%) and (Stx2; 26.67%)
acquired from Shiga toxin producing E. coli (STEC) and two
enterotoxigenic E. coli (ETEC) adhesions(F41; 16.67%) and (F5;
13.3%) (Emad, A.H., and Hend, M.El. D.,
et al., 2016).This
process in which bacteria communicate is known as “quorum sensing” which often
results in the synthesis of physical structures with unique characteristics
known as “biofilms”.A biofilm is a surface association of microbial community
that is imbedded in a self-produced, extra cellular polymeric matrix.These
discoveries make entirely a new field has emerged in basic and applied
microbiology called “Quorum Sensing” (QS).Though not newly to the environmental
microbiologists, persistent infection due to biofilm formation is sure a new
and additional load to clinicians who treat infections (Sritharan, M.,
Sritharan, V., et al., 2004).
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is the
causative agent of various outbreaks of bloody diarrhea and hemolytic-uremic
syndrome all around the world.Quorum Sensing has been shown to be a Global Regulatory Mechanism in
Enterohemorrhagic Eschericha
coli O157:H7 (Sperandio, V., et al .2001).
