The Involvement of Leptospira Spp. in Swine Abortion and Susceptibility of the Pathogen to Antibiotics

Author(s): Gemerlyn G Garcia, Marylaine Ivy M Dioses

The involvement of Leptospira spp. in thirty-five (35) out of fifty (50) cases of swine abortion was investigated which further required evaluation of pathogen susceptibility to a panel of antibiotics. Samples of urine from aborting sows were collected to recover the pathogen, amplify its 16S rRNA gene to confirm its identity and monitor cell density in McFarland Units (MFU) as a measure of susceptibility to antibiotics. The study permitted the isolation and evaluation of Leptospira spp. morphology, demonstration of 3 amplicon products of the 16S rRNA genes with molecular sizes of 1050 to 1080 bp and identification of 2 Leptospira spp. and L. hyos after gene sequencing. The susceptibility of the identified L. hyos to Cephalexin, Neomycin, Clindamycin, Ciprofloxacin and Sulfamethoxazole prepared at different concentrations (25 µg, 35 µg and 50 µg) and evaluated after 6 and 12 hour-exposure time was marked by lower cell densities of recovered L. hyos relative to the application of higher (35 µg and 50 µg) antibiotic concentrations. Significant reduction in cell densities at 12-hr compared to data obtained on the 6-hour were demonstrated and underscored the susceptibility of L. hyos as effects of antibiotic concentration and duration of exposure time. The bactericidal action of 25 µg Ciprofloxacin; and 25 and 35 µg Sulfamethoxazole against L. hyos were established at 6-hour exposure time and that this bactericidal action was maintained until the 12-hr with the application of Neomycin and Ciprofloxacin at 35 and 50 µg and Sulfamethoxazole at 50 µg. These data highlight usefulness of the antibiotics in the treatment of abortion-associated Leptospira infections when administered at the concentrations described.