Short-course and single-dose antimicrobial therapy for chancroid in Kenya: studies with rifampin alone and in combination with trimethoprim.

Tetracyclines and sulfonamides are no longer effective for the treatment of chancroid in many parts of the world. Rifampin and trimethoprim both possess in vitro activity against Haemophilus ducreyi, the causative agent of chancroid. In a randomized, controlled study, 22 patients with H. ducreyi-positive genital ulcers received 600 mg of rifampin once daily for three days, and 32 patients received 600 mg of rifampin plus 160 mg of trimethoprim once daily for three days. Both regimens rapidly eradicated H. ducreyi from ulcers, with subsequent healing of ulcers and buboes. Two relapses of ulcers and one therapeutic failure were observed in the rifampin-trimethoprim group, whereas no relapses or failures were noted in the rifampin group. In addition, all of 16 H. ducreyi-negative ulcers responded rapidly to treatment with either regimen. In an uncontrolled, open study, 22 H. ducreyi-positive ulcers were treated with a single dose of rifampin (600 mg) plus trimethoprim (160 mg). Ulcers and buboes resolved by day 14 in all but one patient. Thus, these short-course and single-dose regimens are effective against chancroid.