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Pasteurellosis is an infection with a species of the bacteria genus Pasteurella, which is found in humans and animals. (Until taxonomic revision in 1999, Mannheimia spp. were classified as Pasteurella spp., and infections by organisms now called Mannheimia spp., as well as by organisms now called Pasteurella spp., were designated as pasteurellosis. The term "pasteurellosis" is often still applied to mannheimiosis, although such usage has declined.)
Pasteurella multocida (P. septica) is carried in mouth and respiratory tract of several animals, notably cats. It is a small Gram negative bacillus with bipolar staining by Wayson stain. In animals it can originate fulminant septicaemia (chicken cholera), but is also a common commensal.
Pasteurellosis in humans is associated with a close animal contact, and may be transmitted by cat or dog bite.
There are several forms of the infection:
- Skin/subcutaneous tissue disease is a septic phlegmon that develops classically in the hand and forearm after cat bite. Inflammatory signs are very rapid to develop; in 1 or 2 hours, edema, severe pain and serosanguineous exudate appear. Fever, moderate or very high can be seen along with vomiting, headache and diarrhea. Lymphangitis is usual. Complications are possible, in the form of septic arthritis, osteitis or evolution to chronicity.
- Sepsis is very rare, but can be as fulminant as septicaemic plague, with high fever, rigors and vomiting, followed by shock and coagulopathy.
- Pneumonia disease is also rare and appears in patients with some chronic pulmonary pathology. It usually presents as bilateral consolidating pneumonia, sometimes very severe.
Pasteurellosis in animals
P. multocida causes numerous pathological conditions in domestic animals. It often acts together with other infectious agents, like Chlamydiae, Mycoplasmae and viruses. Environmental conditions (transportation, housing deficiency, and bad weather) also play a role.
The following diseases are considered caused by P. multocida, alone or associated to other pathogens:
- Shipping fever in cattle and sheep. ("Shipping fever" may also be caused by Mannheimia haemolytica, in the absence of P. multocida, and M. haemolytica serovar A1 is known as the most common cause of the disease. The pathologic condition commonly arises where the causative organism becomes established by secondary infection, following a primary bacterial or viral infection, which may occur after stress, e.g. from handling or transport.)
- Enzootic pneumonia of sheep (and goats, with frequent intervention of Mannheimia haemolytica)
- Fowl cholera (chicken and other domestic poultry and cage birds)
- Enzootic pneumonia and atrophic rhinitis of pigs
- Pasteurellosis of chinchillas
- Pasteurellosis of rabbits
Diagnosis is made with isolation of Pasteurella multocida in a normally sterile site (blood, pus or CSF).
As the infection is usually transmitted into humans through animal bites, antibiotics usually treat the infection, but medical attention should be sought if the wound is severely swelling. Pasteurellosis is usually treated with high dose penicillin if severe. Either tetracycline or chloramphenicol provides an alternative in beta-lactam intolerant patients. Most importantly, treat the wound.
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