Submitted to: Journal of Clinical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 26, 1995
Publication Date: N/A
Interpretive Summary: Leptospirosis, caused by infection with various serovars of the bacterium Leptospira interrogans, is a zoonotic disease which causes systemic illness, abortions, stillbirths, and death in domestic animals and humans. Serovar pomona is a common cause of leptospirosis in cattle, swine, and horses in the United States. Swine, skunks, and opossums are maintenance hosts for serovar pomona in the United States and serve as reservoirs of infection for other animals and man. The epidemiology of pomona infections and the path of transmission of this organism from one species to another has not been clear. This study examined 147 isolates of serovar pomona from cattle, swine, horses, and wildlife to detect genetic differences between the isolates. Six distinct genetic patterns or profiles were detected among the isolates. Multiple isolates from the same outbreak of leptospirosis had identical patterns indicating the stability of the genetic variants. Genetic profiles were found to correlate closely with the animal source of the isolate. Isolates from swine had distinct profiles from cattle isolates. This information will be useful to scientists and veterinarians in epidemiological investigations of leptospirosis outbreaks and in understanding the path of transmission of serovar pomona among species.
Technical Abstract: Isolates (n=147) of Leptospira interrogans serovar pomona were examined by restriction endonuclease analysis. Serovar pomona isolates were obtained from cattle, pigs, horses, and wildlife in North and South America. All isolates were identified as serovar pomona type kennewicki based on EcoRI digestion patterns which were identical to those of the reference strain of fthis serovar. Restriction fragment length polymorphisms were identified i HpaII digestion profiles of the isolates. Six distinct patterns were produced and the patterns correlated with the host animal source of the isolate. Seventy-seven percent of the isolates from swine had HpaII profile 1, whereas only 13.5% of cattle isolates had profile 1. The correlation of DNA RFLP patterns and host was consistent despite the broad geographic distribution of the isolates. Multiple isolates from a single outbreak of leptospirosis were examined and the REA profiles of each isolate were identical. These results indicate that although there is genetic heterogeneity among serovar pomona type kennewicki isolates, that the organism is stable within an outbreak.