Distribution of tet(H) among Pasteurella isolates from the United States and Canada

Tetracycline-resistant isolates of Pasteurella multocida and Pasteurella haemolytica obtained from various locations in the United States and Canada were studied to determine the distribution of the tet(H) gene. OF the 31 isolates examined, 25 were found to contain the tet(H) gene. Chromosomal or plasmid DNA obtained from those that did not contain the fet(H) gene did not hybridize with probes specific for classes A through G, though chromosomal DNA from one isolate lacking tet(H) hybridized with a probe specific for class hi. The tel(PI) gene vas found on plasmid as well as on chromosomal DNA, suggesting that it is carried on a transposable element.