A novel combination of selective agents for isolation of Leptospira species

A novel combination of antimicrobial agents (sulfamethoxazole, 40 mu g/mL; trimethoprim, 20 mu g/mL; amphotericin B, 5 mu g/mL; fosfomycin, 400 mu g/mL; and 5-fluorouracil, 100 mu g/mL) was developed for selective isolation of leptospires from contaminated samples. The growth of 16 microorganisms considered as possible contaminants during isolation of Leptospira were inhibited by this antimicrobial cocktail. In contrast, the growth of a smaller inoculum (101 cells per mL) of 25 Leptospira strains (representing 18 serovars/serogroups of 5 species) was not suppressed by this antimicrobial combination. This cocktail, after being incorporated into Leptospira growth medium (Korthof's), successfully detected leptospires in environmental soil and water. Based on the results, this selective medium has the potential to meet the existing need for an effective selective medium for the isolation of Leptospira.