Evaluation of the in vitro activity of seven selected antimicrobial agents to be used for the isolation of human intestinal spirochaetes.

This study aimed at making a comparative assessment of the growth of pure cultures of Human Intestinal Spirochaetes (HIS) in a control medium without antibiotics and in media including antibiotics (spectinomycin, rifampin, colistin, polymyxin B, amphotericin B, vancomycin, spiramycin) whose use had been indicated in the literature in connection with the isolation of HIS or animal intestinal spirochaetes. All the strains of HIS tested grew in media to which appropriate concentrations of those drugs had been added giving a final number of CFU/ml +/- 10 times the number of CFU/ml observed in the control medium. These results indicate that a selective medium to be used for the isolation of HIS may include appropriate concentrations of one or more of the following antibiotics: spectinomycin (100-1,000 micrograms/ml), rifampin (10-30 micrograms/ml), vancomycin (6.25 micrograms/ml), colistin (6.25 micrograms/ml), polymyxin B (5 micrograms/ml), spiramycin (1-10 micrograms/ml) and amphotericin B (0.05-35 micrograms/ml).