Comparative study of ceftriaxone and trimethoprim-sulfamethoxazole for the treatment of chancroid in Thailand.

A single dose of ceftriaxone (250 mg) administered intramuscularly was compared with trimethoprim-sulfamethoxazole (TMP-SMZ; 160/800 mg) administered orally twice daily for seven days or with a single dose of TMP-SMZ (640/3,200 mg) administered orally for the treatment of chancroid in men in Thailand. Haemophilus ducreyi was isolated from 79 (48%) of 164 men with a clinical diagnosis of chancroid. For men with ulcers that were culture positive for H. ducreyi, rates of cure were 100% in 25 men treated with ceftriaxone, 87% in 23 men given TMP-SMZ for seven days, and 55% in 31 men given TMP-SMZ in a single dose. For men with ulcers that were culture negative for H. ducreyi, rates of cure were 100% in 29 men treated with ceftriaxone, 66% in 32 men given TMP-SMZ for seven days, and 63% in 24 men given TMP-SMZ in a single dose. The MIC50 of the three antibiotics for 94 isolates of H. ducreyi were as follows: 0.004 micrograms/ml for ceftriaxone, 16 micrograms/ml for trimethoprim, and greater than 512 micrograms/ml for sulfamethoxazole. Our study indicates that ceftriaxone in a single dose of 250 mg is effective, but that TMP-SMZ, even when given in a standard seven-day regimen, is not effective treatment for chancroid in Thailand.