VIOLIN: Vaccine Investigation and Online Information Network

Pathogen Page

Pasteurella multocida

I. General Information

1. NCBI Taxonomy ID:

2. Disease:

Pasteurellosis, fowl cholera

3. Introduction

Pasteurella multocida is a Gram-negative, non-motile coccobacillus that is penicillin-sensitive and belongs to the Pasteurellaceae family. It can cause a zoonotic infection in humans, which typically is a result of bites or scratches from domestic pets. Many mammals and fowl harbor it as part of their normal respiratory microbiota, displaying asymptomatic colonization. P. multocida is the most common cause of infection from animal injuries (pneumonia in cattle and pigs, atrophic rhinitis in pigs and goats, and wound infections after dog/cat-bites.) A high leukocyte and neutrophil count is typically observed, leading to an inflammatory reaction at the infection site (generally a diffuse localized cellulitis). It can also infect other locales, such as the respiratory tract. In more serious cases, a bacteremia can result, causing an osteomyelitis or endocarditis. The bacteria may also cross the blood-brain barrier and cause meningitis (Wiki: P. multocida).

4. Microbial Pathogenesis

In birds, P. multocida is believed to enter through the respiratory tract tissues of the host. P. multocida has been shown to adhere to air sac macrophages. The mode of transfer from the lungs to the bloodstream is poorly understood, but heterophils may play a role in the process (Harper et al., 2006).

5. Host Ranges and Animal Models

P. multocida causes can cause disease in fowl, pigs, cattle, rabbits and humans (Harper et al., 2006).

6. Host Protective Immunity

The first systemic host defence used against most invading bacteria involves the innate immune system and includes phagocytosis and bactericidal properties of serum components such as complement. However, P. multocida has mechanisms to evade this system, including the presence of a capsule. Active immunity against P. multocida infection is mainly humoral; vaccination of birds with killed P. multocida stimulates protection against homologous challenge, and opsonization studies in mice have shown that bactericidal antibodies are produced (Harper et al., 2006).

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