Porcine Pasteurella multocida Infection – NAVLE Study Guide

Overview and Clinical Importance

Pasteurella multocida is a Gram-negative coccobacillus that represents one of the most economically significant respiratory pathogens in swine production worldwide. While it is a normal inhabitant of the porcine upper respiratory tract and can be isolated from most swine herds, P. multocida becomes a major pathogen when host defenses are compromised. The organism is primarily known as a secondary opportunistic pathogen in porcine respiratory disease, causing pneumonic pasteurellosis when the mucociliary apparatus is damaged by primary pathogens.

Understanding P. multocida infection is crucial for NAVLE because it commonly appears in questions about the Porcine Respiratory Disease Complex (PRDC), differential diagnosis of pneumonia in finishing pigs, and antimicrobial treatment selection for swine respiratory disease.

Etiology and Microbiology

Organism Characteristics

Pasteurella multocida belongs to the family Pasteurellaceae and is characterized as a Gram-negative, non-motile, facultatively anaerobic coccobacillus that exhibits bipolar staining (safety-pin appearance) with Giemsa or Wright stains. The organism grows readily on standard laboratory media such as blood agar and chocolate agar, producing a characteristic musty odor.