Most clostridia will not grow under aerobic conditions and vegetative cells are killed by exposure to O 2 , but their spores are able to survive long periods of exposure to air. Stained pus from a mixed anaerobic infection. At least three different clostridia are apparent. Clostridium perfringens C. Clostridial hemolysins and extracellular enzymes such as proteases, lipases, collagenase and hyaluronidase, contribute to the invasive process.
Clostridium perfringens also produces an enterotoxin and is an important cause of food poisoning. Usually the organism is encountered in improperly sterilized canned foods in which endospores have germinated. Corned beef is a popular ethnic dish that is commonly served to celebrate St. Patrick's Day. The errors in preparation of the corned beef in this outbreak were typical of those associated with previously reported foodborne outbreaks of C.
Improper holding temperatures are a contributing factor in most C. To avoid illness caused by this organism, food should be eaten while still hot or reheated to an internal temperature of greater than or equal to o F 74 o C before serving.
Gas gangrene Gas gangrene generally occurs at the site of trauma or a recent surgical wound. The onset of gas gangrene is sudden and dramatic.
About a third of cases occur on their own. Patients who develop this disease in this manner often have underlying blood vessel disease atherosclerosis or hardening of the arteries , diabetes, or colon cancer. Clostridium perfringens, Gram Stain. Clostridium tetani is a straight, slender 0. There are 10 serological types of C. Soil, especially that contaminated by animal faeces, is the natural habitat. Clostridium tetani is often transient in the intestines of horses and other animals.
Clostridium tetani produces the exotoxins tetanolysin a haemolysin which may enhance tissue invasion and tetanospasmin a neurotoxin which is plasmid-coded and responsible for the signs of tetanus. The endospores enter traumatic or surgical wounds, especially after castration or docking, via the neonatal umbilicus Fig.
The presence of facultative anaerobes and necrotic tissue create anaerobic conditions and the C. The vegetative cells multiply at the entry site and produce the potent tetanospasmin. This travels via peripheral nerves or blood stream to ganglioside receptors of the motor nerve terminals to which it binds irreversibly.
The toxin travels to the nerve cell body and its dendritic processes in the central nervous system by retrograde intra-axonal flow. The toxin then undergoes transcytosis from the motor neuron to its site of action in the inhibitory neurons.
Tetanus toxin is a bipartite toxin with the light chain being the toxic moiety. The heavy chain mediates attachment and internalization of the toxin. Following internalization which takes place through endocytosis, the low pH of the endosome induces a conformational change in the heavy chain, causing it to form a pore through which the light chain translocates into the cytosol.
The disulphide bridge joining the two chains is reduced in the cytosol. The light chain is a zinc endopeptidase which cleaves synaptobrevin, a vesicle-associated membrane protein. Cleavage of this protein prevents the vesicles containing inhibitory neurotransmitters from releasing their contents, resulting in spastic paralysis and the characteristic tetanic spasms.
Tetanospasmin binds specifically to gangliosides in nerve tissue and once bound cannot be neutralized by antitoxin. When toxin travels up a regional motor nerve in a limb, tetanus develops first in the muscles of that limb, then spreads to the opposite limb and moves upwards. This is known as ascending tetanus and is usually seen only in the less susceptible animals such as dogs and cats.
Descending tetanus is the common form in susceptible species such as humans and horses. In this form toxin circulating in the blood stream affects the susceptible motor nerve centres that serve the head and neck first and later the limbs. Once established, signs of tetanus are similar in all animal species. Note pyogenic infection of umbilicus, the probable portal of entry of C. In tetanus the diagnosis is often based on the history and on the characteristic clinical signs.
This is not completely diagnostic as other clostridia such as C. Clostridium tetani is haemolytic and on normal blood agar tends to have a spreading, swarming growth Figs Oblique illumination.
Clostridium tetani liquefies gelatin but does not ferment the usual range of carbohydrates. Other reactions are given in Table Alternatively, PCR-based procedures can be used to identify C. Demonstration and identification of the toxin is more important than the isolation and identification of the bacterium. In the protection test the animals are protected with antitoxin at least two hours before inoculation with the material containing toxin.
The control mice show typical signs of tetanic spasm in the region of inoculation Fig. Clostridium botulinum is a straight rod 0. Four phenotypically distinct groups of C. In addition, seven types of C. Eight different neurotoxins are produced by C. Figure 1. Clostridium perfringens Main Types of Clostridium Clostridium contains around species that include common free-living bacteria, as well as important pathogens.
Clostridium botulinum Clostridium botulinum can produce botulinum toxin in food or wounds and can cause botulism. There are some clostridium botulinum related products for research use: C. There are some clostridium difficile related products for research use: C. There are some clostridium perfringens related products for research use: C.
Perfringens C. Perfringens NA C. Clostridium sordellii Clostridium sordellii is a rare bacterium that causes pneumonia, endocarditis, arthritis, peritonitis, and myonecrosis. Diagnosis for Clostridium Toxins produced by Clostridium bacteria can usually be detected in a sample of stool.
Several main types of lab tests exist, and they include: Enzyme immunoassay. Polymerase chain reaction PCR. New York. Clostridial myonecrosis: new insights in pathogenesis and management.
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