Isolation of leptospires from the renal tissues of hamsters experimentally infected by Leptospira interrogans serovar pomona. Use of the Pasteur pipette ... with 5-fluor-uracil or neomycin sulfate

Abstract

In order to comparatively study the methods of “in vitro" isolation of leptospires, the Pasteur's pipette and the serial dilution techniques were performed on the renal tissue samples of 60 hamsters experimentally infected either by two strains of Leptospira interrogans serovar pomona, using the Fletcher's medium added with 100 micrograms /mL of 5-fluor-uracil or 2.5 micrograms /mL of neomycin sulfate. The hamsters were divided into groups A and B, the 30 animals of group A were inoculated with a strain of Leptospira that was passed 39 times in hamsters, and the remaining 30 animals, inoculated with a field isolate of Leptospira with only 2 passages in hamsters. The hamsters died three to seven days after the inoculation, or sacrificed in agonic state, and the presence of leptospires in the renal tissue was confirmed by at least one of the three microscopic examination procedures: direct examination of the renal tissue suspension with dark field microscopy, Levaditi’s histologic staining and the direct fluorescent  antibody technique. The specimens taken from the group A were found to be richer in the number of leptospires than the materials of group B. The results of "in vitro" cultivation of leptospires varied according to the strain of leptospires tested. For the group A, the serial dilution technique was the most sensitive, combined with the use of 5-fluor-uracil. For the group B, there was not found any statistical difference at the α = 0 ,0 5 among the isolation techniques, however, the medium added with 5-fluor-uracil showed better results (p < 0,001 and p = 0 ,0 24), respectively for the Pasteur's pippete and for the serial dilution technique.