Pasteurellosis
Pasteurellosis is an infection caused by the bacterium *Pasteurella multocida*, which is commonly found in the upper respiratory tracts of domestic pets, livestock, and poultry. This condition often arises from contact with these animals, particularly through bites, scratches, or even through an animal licking an open wound. Symptoms typically manifest within a day and include severe inflammation, pain, redness, swelling, and systemic signs such as fever and chills. Complications can extend to joint and bone infections, emphasizing the need for prompt medical intervention.
Certain groups, such as children, the elderly, and individuals with compromised immune systems or chronic respiratory conditions, are at higher risk for developing pasteurellosis. Diagnosis is often aided by a patient's history of animal exposure and laboratory tests identifying the bacteria. Treatment usually involves thorough wound cleaning and antibiotic therapy, which is effective in most cases. Preventive measures include immediate medical attention after animal bites or scratches, particularly for those in high-risk categories. Understanding pasteurellosis is crucial for individuals who have frequent interactions with animals, as awareness and prompt action can significantly improve outcomes.
Pasteurellosis
- ANATOMY OR SYSTEM AFFECTED: Eyes, heart, joints, lungs, respiratory system, skin, tissue
- ALSO KNOWN AS: Shipping fever, snuffles
Definition
Pasteurellosis is an infection caused by the bacterial organism Pasteurella multocida, which normally lives in the bodies of domestic pets, livestock, and poultry. Because humans frequently associate with these animal species, most cases of pasteurellosis in humans result from animal contact.
Causes
P. multocida commonly lives in the upper respiratory tract of many domesticated animals, and most cases of pasteurellosis are contracted through animal bites or scratches or through an animal licking a person’s open wound. Dissemination of such infections can also result in joint, heart, eye, and central nervous system infections. Inhaling bacteria as a result of animal contact can also cause respiratory pasteurellosis in persons with underlying medical conditions.
Risk Factors
Children who play roughly with domestic pets are at risk of animal bites. Older persons are also at risk for disseminated disease, as are people with underlying lung conditions such as chronic obstructive pulmonary disease and persons with diabetes, liver disease, or conditions that prevent the immune system from functioning properly.
Symptoms
Pasteurellosis symptoms usually appear one day after receiving an animal bite and include extensive soft-tissue inflammation that is marked by pain, redness, swelling, and the feeling of heat. Later, infected persons develop cellulitis (diffuse inflammation of connective tissue and the lower layers of the skin) and abscesses (pus accumulation). Symptoms also include fever and chills and swelling of the local lymph nodes (lymphangitis). Complications include inflammation of the fluid-filled sheath (synovium) that surrounds tendons (tenosynovitis), bone infections (osteomyelitis) and invasion of joints by bacteria (septic arthritis).
Screening and Diagnosis
A person’s medical history usually reveals routine or recent animal exposure. Also, a Gram’s stain of fluid from inflamed tissues or pus will show pink-staining (gram-negative) bacteria that look like nonuniform short rods (coccobacilli). In cases of septic arthritis, aspiration of the affected joint (arthrocentesis) will show gram-negative coccobacilli. Antibiotic susceptibility tests can distinguish between P. multocida, which is sensitive to penicillin and cephalosporin antibiotics, and those bacterial species that have a similar appearance.
Treatment and Therapy
Washing and irrigating wounds reduces the number of bacteria and improves the infected person’s prognosis. Heavily infected tissue may require surgical debridement.
Pasteurellosis responds favorably to antibiotic treatment. Infected animal bites tend to contain mixtures of various microbes and, therefore, wide-spectrum agents are used in such cases. These antibiotics include cefuroxime and amoxicillin-clavulanic acid (Augmentin), minocycline, ciprofloxacin, ofloxacin, levofloxacin, moxifloxacin, and trimethoprim-sulfamethoxazole. Milder soft-tissue infections are treated for seven to ten days, and more severe infections usually require treatment for ten to fourteen days. Deep-tissue infections initially require intravenous infusions of antibiotics, followed by oral treatments for four to six weeks.
Prevention and Outcomes
Persons who have been bitten or scratched by an animal should gently clean the area around the wound and should seek immediate medical attention as soon as any signs of infection appear. People at high risk, such as those with subfunctional immune systems, rheumatoid arthritis, or prosthetic joints, should seek medical attention immediately after any animal bite or scratch.
Bibliography
Gladwin, Mark, and Bill Trattler. Clinical Microbiology Made Ridiculously Simple. 4th ed. Miami: MedMaster, 2007.
Lacasse, Alexandre, et al. “ Pasteurella multocida Infection.” Available at http://emedicine.medscape.com/article/224920-overview.
Piorunek, Marcin, Beata Brajer-Luftmann, and Jeroslaw Walkowiak. "Pasteurella Multocida Infection in Humans." Pathogens, vol. 12, no. 10, 1 Oct. 2023, p. 1210, doi: 10.3390/pathogens12101210. Accessed 4 Feb. 2025.
Ryan, Kenneth J., and C. George Ray, eds. Sherris Medical Microbiology: An Introduction to Infectious Diseases. 5th ed. New York: McGraw-Hill, 2010.