Shiga furthermore, the highest outbreak of this disease

toxin Escherichia coli (STEC) or Verotoxin producing Escherichia coli (VTEC) O157:H7 is an
important pathogen of diarrhoea, hemorrhagic colitis (HC), and the hemolytic uremic
syndrome (HUS) (Nataro and Kaper, 1998).It commonly take a week to reacquire
from E. coli O157: H7 caused diarrhea, furthermore, some people sensitive
to E. coli O157: H7 strains could sometimes arise Hemolytic Uremic
Syndrome (HUS), which possibly lead to dangerous kidney failure and even extends
to death (Sanchez A, Navarro RB,
2008).Verotoxin producing Escherichia coli (VTEC) arise as a
crucial human pathogens in the last two decades.The hemolytic uremic syndrome
(HUS) comes ~15% of culture proven childhood Escherichia coli O157:H7 contagions and takes place ~1 week later
on diarrhea begins (Wong, C.S., Jelacic, S., Heebib, R.L., etal,2000).STEC
O157:H7 is thought to be the single most significant STEC serotype, though
non-O157 VTEC have contributed to both sporadic cases and large incidence (Goldwater,
P.N., Bettelheim, K.A.1998).Several E. coli strains have been known to
cause haemorrhagic colitis in humans; furthermore, the highest outbreak of this
disease were detected in relative to O157:H7 (Scotland SM, Willshaw GA, Smith
HR, Rowe B.1990).Globally
non-O157:H7 STEC were most commonnly causes of HUS reported like in Australia,
Germany, and Austria (Phillip, Tarr, I., Carrie, Gordon, V., Wayne, Chandler,
L., 2005).Escherichia coli O157   is the most common member  of pathogenic E. coli strains known diversely as enterohaemorrhagic,
verocytotoxin producing and Shiga-toxin-producing organisms.The ?rst outbreaks
induced by E. coli O157 took place in Oregon and Michigan, USA, in 1982, when it
was isolated from individuals who arise bloody diarrhea and serious abdominal
cramps after eating hamburgers in a restaurant (MMWR Morb Mortal Wkly Rep.

Diarrheagenic Escherichia coli (DEC) can be classified as
pathotypes on the basis of gene-specific sequences.The six known pathotypes
include Diffusely adherent E. coli (DAEC)  Enteroinvasive E. coli  (EIEC), Enterotoxigenic E. coli (ETEC),
Enteropathogenic E. coli (EPEC), Enteroaggregative E. coli
(EAEC), and Enterohemorrhagic E. coli (EHEC) (Iruka, I.N., et al., 2009).VTEC
have twenty-five  serogroups identified
in this study and included four serogroups (077, 096, 0140, and 0162) not
previous described.Out of twenty-five (25) serogroups, fourteen serotypes
(02,04,07,08,09,015,(GI-0,022,026,0110,0113,0126, 0157 and 0168) have been
asoociated with human disease(CH and HUS) (Smith, H.R., Scotland, S.M.1988).It
is  recently observed that STEC as
important food-borne pathogens, especially O157, O26, O103, O111, O145, O45,
O91, O113, O121 and O128 serogroups (Momtaz, Farzan, Rahimi, Safarpoor
Dehkordi, & Souod, 2012).Within
each pathotype, E coli strains are further characterized according to
antigenic variants including O-antigen (lipopolysaccharide), H-antigen
(flagellar) and K-antigen (capsular) types (Riley LW, Remis RS, Helgerson SD,zaet al.1983).STEC
expressing somatic (O) antigen 157 and ?agellar (H) antigen and contain seven
(7) serotype most frequently isolated from human beings, and these serotype
with the potent and most bearing etiological affiliation with HUS.Strains which
express the lipopolysaccharide (LPS) O-antigen 157 (O157 strains) are usually
associated with serious clinical manifestations,including bloody diarrhea,
hemorrhagic colitis, and hemolytic uremic syndrome (Tarr, P.I. et al., 1995).A
highly conserved, non-conjugative F-like plasmid, related to pO157, which
ranges in size between 92 kb and 104 kb are mostly bears by EHEC
O157:H7.Sequence analysis shows a heterogeneous mixture conveys of genetic
elements, transposons and prophages, as well as parts of other plasmids which,
collectively, are indicative of its splotched evolution.The complete sequence
of pO157 shows 100 open reading frames; among them, 43 indicate similarities to
known proteins.However, the exact role of pO157 in disease pathogenesis is
still  not well known because published
studies have reported contradictory findings (Lim JY, Yoon J, Hovde CJ. 2010).The
dominant STEC serotype is O157:H7; it is the serotype most commonly involved in
large outbreaks (Paton, A.W., and Paton, J.C.1998).Shiga toxins (Stx1 and Stx2) or verotoxins (VT1 and VT2) are two potent phage-encoded
cytotoxins of STEC.Stx1 and Stx2 are further classified into several
subtypes; according to the new categorization suggested by Scheutz et al.
(Scheutz, F., Teel, L.D., and Beutin, L., et
al., 2012).Stx1 consists of three variants, Stx1a, Stx1c and Stx1d, whereas Stx2 is a diverse group composed of seven distinguishable variants, namely Stx2a,
Stx2b, Stx2c, Stx2d, Stx2e, Stx2f and Stx2g.The
production of Stx may not be alone
responsible for pathogenesis of STEC (Farfan, M.J., and Torres, A.G.2012).In addition to toxin production, another virulence-associated factor carried by STEC is a protein called intimin which is responsible for attachment of STEC to the intestinal epithelial cells, causing attaching and effacing (AE) lesions in the intestinal mucosa.The chromosomal gene eae, called intimin which is component of a pathogenicity island termed the locus for enterocyte effacement (LEE).Enterohaemolysin (Ehly), is a factor 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).Acid
resistance (AR) is the ability of bacteria to protect themselves from extremely
low pH (

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