Abstract
Klebsiella pneumoniae was isolated from lesions in 2 dead and 82 ill animals in a breeding colony of 2300 Wistar rats. The clinical signs were unilaterial and bilateral fluctuating masses in the cervical and inguinal areas, and focal cutaneous ulcers in the ventral neck. Cervical and inguinal lymphadenitis with abscess formation were found on microscopic examination. Lesions also occurred in visceral organs. Although characteristic of the natural infection in most species, no respiratory lesions were seen in this epizootic episode. A capsular serotype 5 K. pneumoniae which did not utilize malonate was the only bacterial strain cultured from the lesions, but other K. pneumoniae strains that utilized malonate and were untypable by capsular serology were cultured from throats and faeces. 30% (6/20) of asymptomatic animals tested had both types of K. pneumoniae in their faeces.