IN VITRO SENSITIVITY OF LEPTOSPIRA TO VARIOUS ANTIMICROBIAL AGENTS

Abstract

The in vitro sensitivity of Leptospira icterohaemorrhagiae was checked against 14 antimicrobial agents to find which might be added to leptospira culture media to control contamination without seriously depressing growth of leptospires. Estimates of the amounts of leptospira growth resulting in these modified media suggested that five agents were worthy of further study. The determination of leptospira population by microscopic counts showed that three of these compounds produced only slight to moderate inhibition. Two of these three antimicrobial compounds plus a fungicide were tested in combinations. Qualitative tests on these media were also carried out employing L. ballum, L. canicola, L. pyrogenes, and L. sejroe.Based on results of these tests, a new selective medium for growing leptospires is suggested; it consists of a standard leptospira liquid medium to which are added 50 mg/l. sulfathiazole, 5 mg/l. neomycin sulphate, and 0.5 mg/l. actidione.