Randomly amplified polymorphic DNA polymerase chain reaction assay for molecular epidemiologic investigation of Pasteurella pneumotropica in laboratory rodent colonies.

After an episode of clinical Pasteurella pneumotropica infection was diagnosed in a C57BL/6N mouse, a randomly amplified polymorphic DNA polymerase chain reaction assay (RAPD-PCR) was developed and used to genetically characterize and differentiate 52 field isolates and laboratory reference strains of P. pneumotropica and related bacteria. A survey of rodents in the facility recovered 36 isolates of P. pneumotropica from 30 mice, six isolates from hamsters, and three isolates from rats during the follow-up investigation. Antibiograms and routine bacteriologic evaluations for morphologic and biochemical characteristics on selective media did not substantively aid in the differentiation of these isolates, but the RAPD-PCR revealed four strains of P. pneumotropica in the colony, two of which were confined to rats and hamsters. The RAPD-PCR unambiguously differentiated Heyl and Jawetz biotypes of P. pneumotropica recovered from mice, identified two additional genetic groups for rat and hamster isolates, and clearly distinguished P. pneumotropica from related bacteria. Most field isolates were genetically consistent with the Jawetz biotype of P. pneumotropica. The RAPD-PCR is a fast, sensitive, and efficient method for identifying genetic differences between strains of the P. pneumotropica complex and can contribute substantially in addressing the epidemiology, pathogenesis, and taxonomic classification of this common opportunistic pathogen.