3. Introduction
Enteric bacterial diseases
Etiologic bacteriological diagnosis by classical cultures
techniques do not allow detection and identification of the
most frequent diarrheagenic Escherichia coli in our
countries as enteropathogenic E. coli (EPEC) and
enterohemorrhagic E. coli (EHEC).
4. EPEC is a leading cause of diarrhea in developing
countries.
In industrialized countries, the frequency of these
organisms has decreased, but they continue to be
an important cause of diarrhea .
5. EPEC was first reported by John Bray in 1945
as the cause of diarrhea outbreak in London
5
6. Classification of Enteropathogenic E. coli
Pathotype Clin Features Epidem. Features Virulence factors
EPEC Watery diarr., Infants, Bundle forming pilus,
vomiting Developing attaching-effacing
countries
EHEC Watery diarr., Food & water Shiga toxins, attaching-
Hg. colitis borne effacing
ETEC Watery diarr Childhood diarr., Pili, ST & LT entero
Traveler's diarr. toxins
EAEC Diarr with Childhood diarr. Pili, cytotoxins
mucus
EIEC Dysentery/ Food borne Cellular invasion, intra
watery diarr cellular motility
12. Primer Design
Primer Name
5’-GGA AGT CAA ATT CAT GGG GGT AT bfp F
bfp R
5’-GGA ATC AGA CGC AGA CTG GTA GT
13. PCR and Gradient PCR
Temperature Time Cycle(s)
Gradient PCR 94 5 min 1
for samples
g=5 94 45 sec
52 1min
40
72 1min
72 5 min 1
Primer F 1 l
Primer R 1 l
10mM dNTP Mix10X Taq 22 l
buffer Containing 1. 5mm
MgCl2
Taq Polymerase 1U
DNA 1 l
14. Gel agarose electrophoresis
1 2 3 4 5 6 7 8
PCR Product= 250 bp
1= ladder 100bp plus fermentas
2-7 = sample
8 = negative control
250 bp
The diarrhea and other symptoms of EPEC infections probably are caused by bacterial invasion of host cells and interference with normal cellular signal transduction, rather than by production of toxins.
Studies with adult volunteers have demonstratedthat intimin, pEAF and BFP are essential virulence deter-minants of EPEC [10-12]. Interestingly, there is evidencethat a subset of EPEC strains, known as atypical EPEC(aEPEC), which lack pEAF and BFP, are also pathogenic
EPEC strains may be either typical, producing bundle forming pili(encoded by the bfpA gene) that mediatelocalised adherence on cultured epithelial cells, or atypical, which are negative for these appendages but show localised like adherence,diffuse adherence or aggregative adherence patterns and produce diarrhae in developing worlds.Virulance gene is bfp for typical and non typical
