Effect of Leptospirosis on the Concentrations of Streptomycin in Liver and Kidneys of Pigs

Leptospirosis is a re-emerging infectious disease with zoonotic potential. Pigs are reservoir hosts of the pathogen and streptomycin is among the antibiotics proposed to eliminate leptospiral infection. The purpose of this study was to determine streptomycin concentrations and the possible effect of the presence of Leptospira in the liver and kidneys on drug distribution. Six pigs with leptospirosis and six age, gender and breed matched healthy pigs were intramuscularly administered streptomycin at a dose of 10 mg kg^-1 bodyweight once daily for four consecutive days. Prior to administration biochemistry was employed to evaluate liver and kidney function. All pigs were euthanized and the concentrations of streptomycin in their liver and kidney were determined employing an HPLC-MC method. Infected pigs showed hyperbilirubinaemia and an increase in alanine aminotransferase and alkaline phosphatase activities compared with uninfected controls. Urine specific gravity was reduced in infected pigs, however, without elevated levels of urea and creatinine. A higher mean concentration in both organs-statistically significant only for liver-of healthy pigs was observed. The decreased concentrations of streptomycin in infected pigs could be at least partially attributed to the hepatic and renal damage caused by leptospirae and in turn the possible reduced efficacy of streptomycin to its reduced concentrations at the main sites of infection. Possible alterations of drug concentrations by liver and/or kidney infection by various pathogens including Leptospira should be taken into consideration when determining doses to result in effective drug concentrations at the site of infection.