Tetracycline, sulfisoxazole, and a combination of these two antibiotics were evaluated and compared in the treatment of chancroid. Whereas the effectiveness of sulfonamide drugs in chancroid is supported by this study, tetracycline alone was found to be often inadequate. The difference between this observation and the conclusions of previous studies is noted, and possible explanations for the discrepancy are offered.
Kerber RE, Rowe CE, Gilbert KR. Treatment of ChancroidA Comparison of Tetracycline and Sulfisoxazole. Arch Dermatol. 1969;100(5):604-607. doi:10.1001/archderm.1969.01610290088020