Efficacy of combined furazolidone and neomycin in the control of contamination in Leptospira cultures.

The in vitro effectiveness of furazolidone combined with neomycin for the control of contaminants in Leptospira cultures was investigated. Enhanced additive or synergistic bactericidal activity was apparent with the combination when it was compared with each agent used separately or when compared with 5-fluorouracil. Combined furazolidone and neomycin, at 5-mug/ml concentrations each in Fletcher medium or in implanted sensitivity disks of 50 mug and 10 mug, respectively, was effective in inhibiting contaminants and did not interfere with the growth of leptospira belonging to 66 leptospiral collection serotypes. A simple technique for decontaminating swine kidneys from an abattoir for cultural isolation of leptospiras is described. The method involves exposing renal tissue diluted in saline containing furazolidone and neomycin in combination (each in a concentration of 25 mug/ml) for 1 h prior to inoculating culture media. The method is suitable for routine use in the isolation of leptospiras from contaminated clinical or pathological specimens.