Evaluation of inhibitors for development of a selective medium for isolation of Leptospira spp. from clinical samples.

This study was conducted to develop a selective medium for the detection of Leptospira spp. in clinical samples. Serovars of Leptospira spp., environmental bacteria and the fungus from contaminated cultures of patients with suspected leptospirosis were inoculated into EMJH medium containing amphotericin B, 5-fluorouracil (5-FU), furazolidone and neomycin used singly or combined. Medium with 5-FU at the concentration of 200 mu g ml(-1) did not show any inhibitory effect against the fungus, Gram-negative bacilli and any of the leptospira strains except serovar Pyrogenes. The highest concentration of neomycin and furazolidone that did not inhibit the growth of leptospires was 4 mu g ml(-1). All strains of Leptospira spp. grew on 5-FU (100 mu g ml(-1)) in combination with neomycin (4 mu g ml(-1)) and on 5-FU (100 mu g ml(-1)) in combination with furazolidone (4 mu g ml(-1)). The highest concentration of amphotericin B (500 mu g ml(-1)) that inhibited the growth of the fungus also inhibited the bacteria and most of serovars of Leptospira spp. The most effective antibiotic combinations that inhibited the majority of environmental bacteria growth without affecting leptospiral growth were EMJH with 5-FU (100 mu g ml(-1)) in combination with neomycin (4 mu g ml(-1)). In conclusion, these findings will help the development of new selective media to isolate leptospires.