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.
was first found in 1878 in fowl cholera-infected birds. However, it was not isolated until 1880, by Louis Pasteur
- the man in whose honor Pasteurella
- See: Pasteurellosis
is the most common cause of infection from animal injuries. (Pneumonia in cattle and pigs, atrophic rhinitis in pigs and goats and wound infections, specially after dog/cat-bites.) A high leukocyte
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
. The bacteria may also cross the blood-brain barrier
and cause a meningitis
Virulence, Culturing, and Metabolism
encodes the toxin responsible for most P. multocida virulence factors
. This toxin activates Rho GTPases
, which bind and hydrolyze GTP, and are important in actin stress fiber formation. Formation of stress fibers may aid in the endocytosis of P. multocida
. The host cell cycle is also modulated by the toxin, which can act as an intracellular mitogen
will grow at 37 degrees Celsius on blood
or chocolate agar
, but will not grow on MacConkey agar
. Colony growth is accompanied by a characteristic "mousy" odor due to metabolic products.
Being a facultative anaerobe
, it is oxidase-
, and can also ferment
a large number carbohydrates in anaerobic conditions.
This bacterium can be effectively treated with beta-lactam antibiotics
, which inhibit cell wall synthesis. It can also be treated with fluoroquinolones
; fluoroquinolones inhibit bacterial DNA synthesis
and tetracyclines interfere with protein synthesis
by binding to the bacterial 30S ribosomal
Because P. multocida is most often acquired as a result of a bite (notably dog), infections are frequently polymicrobial and involve anaerobic bacteria. As a result, amoxicillin-clavulanate (a beta-lactamase inhibitor/penicillin combination) is seen as the treatment of choice.