Pasteurella multocida colonization and invasion in experimentally exposed turkey poults

Turkey poults were examined microbiologically to detect colonization and invasion following exposure to selected strains of Pasteurella multocida. A variety of host tissues was examined 24 hours or less after exposure via the upper respiratory tract. Recovery of P. multocida from the dorsal pharynx was used as an indicator of colonization; recovery from selected internal organs was used as an indicator of invasion. The frequency of colonization and invasion by capsulated and uncapsulated forms of an avirulent live-vaccine strain was low. A virulent strain readily colonized and invaded. Colonization occurred in less than 6 hours after exposure, and invasion occurred between 6 and 12 hours after exposure.