avian & livestock assay data sheet
E. coli panel
Qualitative detection and differentiation by PCR of 5
different categories of diarrheagenic
E. coli -- ETEC,
EHEC, EIEC, EPEC and EAEC.
diseases are a major cause of death for children under 5 years
of age in developing countries; the estimated death toll is
12,600 children per day. Causes of diarrhea include a wide range
of viruses, bacteria, and parasites. Among the bacterial
pathogens, various strains of
Escherichia coli are
the major culprits.
E. coli is the
predominant nonpathogenic facultative anaerobic member of the
human intestinal microflora, some
E. coli strains can
cause diseases of the gastrointestinal, urinary, and central
nervous systems in humans. The intestinal tracts of almost all
birds and mammals, including nonhuman primates and horses, are
colonized by E. coli.
Infections by pathogenic strains of
E. coli also occur in many domestic and wild
symptoms induced by these diarrheagenic
E. coli can be due
to production of toxins or other virulence traits.
E. coli strains that
induce diarrhea in their hosts can be divided into five main
categories on the basis of distinct epidemiological and clinical
features and specific virulence determinants:
ETEC - Enterotoxigenic
E. coli: Produce heat-labile toxin (LT) and heat-stable
EHEC - Enterohemorrhagic
E. coli: Produce shiga-like toxins (SLT) I and II.
EIEC - Enteroinvasive
E. coli: Typically invade and destroy the bowel mucosa.
EPEC - Enteropathogenic
E. coli: Damage the bowel mucosa with characteristic
attaching and effacing lesions mediated by a protein encoded
by a gene called the attaching and effacing locus (eal).
EAEC - Enteroaggregative
E. coli: The epidemiology and pathogenicity of these
strains have not yet been clearly defined, but the presence
of a large 60 kD plasmid encoding several virulence factors
and toxins is important for their virulence.
ETEC induce a watery diarrhea in infected hosts by action of the
two toxins, LT and ST. The LT enterotoxin is very similar to
cholera toxin in both structure and mode of action. ST is known
to bind to and activate a guanylate cyclase enzyme located on
apical membranes of host cells. This leads to secretion of fluid
and electrolytes resulting in a watery diarrhea. Incubation
period is approximately 1-2 days and illness can last 3 days to
mostly represented by a single strain, serotype O157:H7, which
causes a diarrheal syndrome with copious bloody discharge and no
fever. There is a toxic effect on the kidneys, and diarrhea
caused by this strain can be fatal, particularly in infants, due
to acute kidney failure. Infection in humans is often associated
with ingestion of inadequately cooked hamburger meat. Incubation
period is approximately 3 to 4 days and duration of illness is
about 1 week.
similar to Shigella in their pathogenic mechanism and clinical
symptoms. EIEC bacteria penetrate and multiply within epithelial
cells of the colon causing widespread cell destruction. The
clinical syndrome is identical to Shigella dysentery and
includes a dysentery-like diarrhea with fever. EIEC do not
produce LT or ST toxin and, unlike Shigella, do not produce
shiga toxin. The incubation period is less than 24 hours.
EPEC cause a
watery diarrhea similar to ETEC, but do not produce ST or LT
toxins. These strains are a principal cause of infant diarrhea
in developing countries. The illness typically lasts 1 to 3
to epithelial cells in a characteristic stacked-brick pattern
known as the aggregative adherence (AA) pattern. When they
adhere to small and large bowel mucosal surfaces they stimulate
mucus production, leading to a thick mucus-containing biofilm
encrusted with EAEC. They can also secrete toxins, such as
heat-stable enterotoxin 1 (EAST1), Pet and Pic, which are
associated with damage to the mucosa. EAEC were originally
recognized as one of the predominant etiologic agents of
persistent diarrhea in developing countries and they remain an
important cause of acute as well as protracted diarrhea in many
parts of the world, including industrialized countries.
assays are available for detection of diarrheagenic
E. coli, including
biochemical reactions, serotyping and phenotypic assays based on
virulence characteristics. However, molecular detection by PCR
has become a commonly-used method to detect and identify these
bacteria because the method gives rapid and reliable results in
addition to its high sensitivity and specificity (Bellin et al.,
2001; Stacy-Phipps et al., 1995).
Help confirm the disease causing agent
Selection of appropriate treatment regimen
Shorten the time required to confirm a clinical
Help ensure that animal groups and populations are free of
diarrheagenic E. coli
Early prevention of spread of diarrheagenic
E. coli among a
group or population
Minimize personnel exposure to diarrheagenic
Safety monitoring of biological products that derive
Bellin, T., Pulz, M., Matussek, A., Hempen, H.G. and Gunzer, F.
(2001) Rapid detection of enterohemorrhagic Escherichia coli by
real-time PCR with fluorescent hybridization probes. J. Clin.
Stacy-Phipps, S., Mecca, J.J. and
Weiss, J.B. (1995) Multiplex PCR assay and simple preparation
method for stool specimens detect enterotoxigenic Escherichia
coli DNA during course of infection. J. Clin. Microbiol.
specimens: Rectal swab, or cloacal swab, or 0.2 ml feces, or 0.2 ml bacterial culture, or
preferred specimen: 0.2 ml whole blood in EDTA (purple top) or
ACD (yellow top) tube.
types other than those listed here, please call to confirm
specimen acceptability and shipping instructions.
specimen types, if there will be a delay in shipping, or during
very warm weather, refrigerate specimens until shipped and ship
with a cold pack unless more stringent shipping requirements are
specified. Frozen specimens should be shipped so as to remain
frozen in transit. See shipping
instructions for more information.
3 business days