Pasteurellosis

Pasteurellosis is an infection with a species of the bacterial genus Pasteurella,^[1] which is found in humans and other animals.

Pasteurella multocida (subsp. septica and subsp. multocida) is carried in the mouth and respiratory tract of various animals, including pigs.^[2] 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.

Until taxonomic revision in 1999,^[3] 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.

Types

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 common. 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.

Other locations are possible, such as septic arthritis, meningitis and acute endocarditis, but are very rare.

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,^[4][5] and M. haemolytica serovar A1 is known as the most common cause of the disease.^[4] 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.^[5])
• 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
• Pasteurellosis suspected in an epizootic illness of saiga antelope, although there are other possible causes.^[6]

Diagnosis

Diagnosis is made with isolation of Pasteurella multocida in a normally sterile site (blood, pus or CSF).

Treatment

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. However, it is most important to treat the wound.

See also

• Hemorrhagic septicemia
• Pasteurellaceae

References

External links

• Pasteurella multocida-related diseases in sheep and goats