is a gram positive, anaerobic, spore forming motile rod bacterium that
commonly inhabits the intestinal tract of many mammalian species,
reptiles and birds. It is also found in the environment. The bacterium
is a highly diverse organism, with more than 400 unique types, and has
several virulence factors. Exotoxin A and B are the most significant
factors, and bacterial production of exotoxins is correlated with
pathogenicity of individual strains of
C. difficile. Toxin A is
an enterotoxin, promoting fluid exudation from the intestinal mucosa,
and acts synergistically with the cytotoxic toxin B through attachment
to specific receptors on the surface of enterocytes. The combined
action of these toxins results in necrosis of superficial epithelium
and edema in affected areas of intestine.
The organism is an important cause of enteric disease in laboratory
rodents and horses. Hamsters, guinea pigs and mice may be affected by
pseudomembranous colitis induced by antimicrobial therapy. In neonatal
foals, C. difficile
has been associated with hemorrhagic necrotizing enterocolitis and
diarrhea. The lack of an established intestinal microflora may make
foals more susceptible to colonization by this bacterium. Adult horses
may develop typhlocolitis and outbreaks of nosocomially acquired
diarrhea have been reported (Donaldson and Palmer, 1999; Madewell et
al., 1995; Perrin et al., 1993).
has also recently been implicated as a cause of typhlocolitis in
nursing piglets, chronic diarrhea in dogs and enterotoxemia in
In clinically normal patients, an established intestinal microflora is
thought to competitively prevent proliferation of
C. difficile and
subsequent toxin attachment. Alteration of intestinal microbial
balance with antibiotic use and increased exposure to the organism in
a hospital setting allows C.
difficile to colonize the gut in susceptible individuals.
Bacterial culture of C. difficile
is not highly sensitive and does not differentiate the pathogenic and
non-pathogenic strains. Specific tests for
C. difficile toxins used
in the diagnostic laboratory include cell culture, which relies on the
presence of biologically active toxin, and an ELISA assay which
detects immunologically active toxin that may or may not be
PCR detection of C. difficile
is highly sensitive and can discriminate between toxigenic and
nontoxigenic strains of the organism by detecting its toxin producing
Clostridium perfringens is a Gram-positive, rod-shaped, anaerobic, spore-forming bacterium found
as a normal component of decaying vegetation, marine sediment, the
intestinal tract of humans and other vertebrates, insects and soil.
Infections due to C. perfringens
can result in tissue necrosis, bacteremia, emphysematous cholecystitis
and gas gangrene. The bacteria can secrete α-toxin which results in
gangrene formation. If patients ingest the bacteria, colic, diarrhea
and sometimes nausea can result.
Food poisoning due to C. perfringens
bacteria is one of the common causes of food-borne illness. Poorly
prepared meat and poultry are commonly the sources of food poisoning.
The enterotoxin (CPE)
secreted by the bacteria, which mediates the food poisoning, is
heat-resistant and cannot be destroyed easily. Furthermore, the
bacteria themselves form spores that can withstand cooking
temperatures. If these spores are then left at room temperature,
germination may begin and infective bacterial colonies develop.
Generally, the incubation time of these spores is 6 to 24 (commonly 10
to 12) hours after ingestion of contaminated food. Since meat and
poultry are often prepared in advance of consumption, this allows good
opportunities for the spores to germinate.
People ingesting these bacteria can develop abdominal cramping
and diarrhea. Vomiting and fever are unusual. Illness usually resolves
within 24 hours. It is also possible that many cases of C.
perfringens food poisoning remain subclinical, as antibodies to
the toxin are common among humans. This has led to the conclusion that
most of the population has experienced food poisoning due to C.
Detection of C. perfringens by
culture is slow and not very sensitive. PCR detection is the method of
choice for rapid, sensitive and specific detection of this pathogen (Abubakar,
Infection with Clostridium
piliforme results in Tyzzer’s disease, which is
characterized by necrotic lesions in the liver, digestive organs and
heart. A number of animal species are susceptible to this organism,
including mice, rats, rabbits, dogs, cats, primates, and horses.
The organism is an obligate gram-negative bacteria found in necrotic
foci in spore forms. Transmission is mainly through the fecal-oral
Although Tyzzer’s is a severe disease in many animal species, infected
mice often do not exhibit clinical symptoms. These mice become
carriers of the disease and spread the pathogen to other mice and
other animal species. Interestingly, different mouse strains differ in
their susceptibility to the pathogen (Waggie et al., 1981).
cannot be cultivated in artificial media, so diagnosis may be based on
microscopic examination of tissues, serological assays or steroid
challenge tests; these methods all require blood or necropsy samples.
When steroid challenge assays are performed, extreme care must be
taken to avoid spreading the pathogen. Moreover, microscopic
examination, serology and steroid challenge all suffer from a lack of
sensitivity and are labor intensive.
Detection of this pathogen by polymerase chain reaction is highly
sensitive and specific. The test can be performed on fecal specimens
rather than blood or tissue, resulting in less trauma and risk to
Help confirm the disease causing agent
Shorten the time required to confirm a clinical
diagnosis of Clostridium
infection to the species level
Help ensure that animal, facilities and populations are free
of these bacteria
Early prevention of spread of these bacteria
Minimize personnel exposure to these bacteria
Safety monitoring of biological products and vaccines
that derive from susceptible animals
I., Irvine, L., Aldus, C.F., Wyatt, G.M., Fordham, R., Schelenz, S.,
Shepstone, L., Howe, A., Peck, M. and Hunter, P.R. (2007) A systematic
review of the clinical, public health and cost-effectiveness of rapid
diagnostic tests for the detection and identification of bacterial
intestinal pathogens in faeces and food. Health. Technol. Assess.
Donaldson, M.T. and Palmer, J.E. (1999) Prevalence of
Clostridium perfringens enterotoxin and Clostridium difficile toxin A
in feces of horses with diarrhea and colic. J. Am. Vet. Med. Assoc.
Madewell, B.R., Tang, Y.J., Jang, S., Madigan, J.E.,
Hirsh, D.C., Gumerlock, P.H. and Silva, J. (1995) Apparent outbreaks
of Clostridium difficile associated diarrhea in horses in a veterinary
medical teaching hospital. J. Vet. Diagn. Invest. 7:343 346.
Perrin, J., Cosmetatos, I., Gallusser, A., Lobsiger, L., Straub, R.
and Nicolet J. (1993) Clostridium difficile associated with
typhlocolitis in an adult horse. J. Vet. Diagn. Invest. 5:99 101.
Waggie, K.S., Hansen, C.T. Ganaway, J.R. and Spencer, T.S.
(1981) A study of mouse strains susceptibility to Bacillus piliformis
(Tyzzer's disease): the association of B-cell function and resistance.
Lab. Anim. Sci. 31:139-142
Rectal swab, or 0.2 ml feces, or food swab, or
lesion swab, or environmental surface swab.
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