E coli PCR test for horses
equine assay data sheet
P0016 - Qualitative detection and differentiation by PCR of 5
different clinically important categories of diarrheagenic
E. coli -- ETEC, EHEC,
EIEC, EPEC and EAEC
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
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 species.
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.
Clinically, 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 several weeks.
EHEC are 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.
EIEC are 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
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 days.
EAEC adhere 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.
Several 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
Help confirm the disease causing agent
Selection of appropriate treatment regimen
Shorten the time required to confirm a clinical
Help ensure that herds are free of diarrheagenic
Early prevention of spread of diarrheagenic
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. Microbiol. 39:370-374.
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. 33:1054-1059.
Rectal swab, 0.2 ml feces or 0.2 ml bacterial culture.
Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.
For all 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
3 business days