Which statement is NOT true about Pasteurella multocida?

• A. Most common human infections occur in soft tissues, bones, and joints.
• B. Humans harbor the organism as part of their normal flora.
• C. It is the most virulent of the species in the genus.
• D. It grows on sheep blood agar.

Answer: (B)

Pasteurella multocida is a zoonotic bacterium carried by many animals, especially the mouths of cats and dogs. In humans it does not live as part of the normal flora; infections typically arise after an animal bite or scratch and most commonly present as cellulitis in the soft tissues. It can also extend to involve bone and joints, leading to osteomyelitis or septic arthritis in some cases. In the laboratory it grows readily on sheep blood agar, forming small colonies that are usually nonhemolytic. While it can be quite virulent in animal infections and can cause significant disease in people after exposure, humans are not regular carriers of this organism as part of their normal microbiota. So the statement claiming human harboring as part of normal flora is not true.