Submitted to: Journal of Clinical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 29, 1997
Publication Date: N/A
Interpretive Summary: Leptospirosis, caused by pathogenic members of the genus Leptospira, is a common disease among wild and domesticated animals. Leptospirosis is an important cause of abortions and stillbirths in livestock. In addition, animals with leptospirosis shed the organism in urine which can result in infection of human beings. When there is an outbreak of leptospirosis, it is important to quickly locate the source of infection to limit the spread of the disease. We developed a method to quickly identify leptospiral isolates from animals and humans. The method can be accomplished in a day as compared to other techniques which take weeks to months. Identification of the isolates is a key tool in identification of the source of infection and therefore in the rational design of control programs. The typing method described here will be of use in leptospiral reference laboratories throughout the world for identification of leptospiral isolates. In addition, the technique can be adapted for use by biologics firms for the validation of seedstocks for vaccine production.
Technical Abstract: Genetic variability among Leptospira interrogans (sensu stricto) serovars was assessed using Southern blot hybridization and PCR analyses. The experiments used probes directed to sequences in a recently described insertion element, IS1500. Hybridization analysis showed that IS1500 was present on polymorphic fragments. The hybridization patterns could be used dto differentiate serovars. When the hybridization analysis was used to characterize isolates of serovar pomona type kennewicki, several new genetic groups were identified. The genetic variations described by IS1500 typing are distinct from recently identified restriction fragment length polymorphisms associated with adaptation to specific host species, but when combined with this method, identifies a total of 15 different genetic groups. The IS-based typing should be useful in epidemiological analysis of serovar pomona isolates. DNA amplified by PCR using primers to IS1500 generated characteristic amplification patterns for different serovars. Hybridization and PCR assays were used to characterize several newly isolated strains of L. interrogans obtained from an area of Nicaragua that recently had an outbreak of human leptospirosis.