Background: Superficial cutaneous fungal infection, principally dermatophytosis, is an extremely common skin disease. Various in vitro test systems have been developed in recent years to determine the antifungal activity of various drugs. The minimum inhibitory concentration (MIC) obtained may give an indication of the in vivo potency of the drugs.
Methods: One hundred patients (69 men and 31 women) with a clinical diagnosis of dermatophytosis were entered into the study. Direct microscopy and culture were done on all patients. The MICS were determined using the broth dilution method.
Results: The age range was 1-76 years. The most common diagnosis was tinea corporis (36%), followed by tinea cruris (22%), and tinea pedis (19%). The most common fungus isolated was T. rubrum (58%), followed by E. floccosum (14%), and T. mentagrophytes (10%). The majority of the isolates was sensitive to the three drugs tested (griseofulvin, ketoconazole, and itraconazole). Of the isolates, 82% were sensitive to griseofulvin, 78% to ketoconazole, and 81% to itraconazole, all at a concentration of < 0.25 micrograms/mL. For T. rubrum, there were four isolates that had an MIC of > or = 64 micrograms/mL to griseofulvin, seven isolates and nine isolates with an MIC > or = 64 micrograms/mL to ketoconazole and itraconazole, respectively. T. interdigitale was relatively resistant to the three drugs in vitro with four of seven isolates having an MIC > or = 4 micrograms/mL with griseofulvin, one of seven isolate with an MIC > or = 64 micrograms/mL with ketoconazole, and three of seven isolates with an MIC > or = 32 micrograms/mL with itraconazole.
Conclusions: The in vitro antifungal activity of griseofulvin, ketoconazole, and itraconazole are similar against dermatophytes in Singapore. Griseofulvin may be given as the first-line drug for treating such infections in Singapore.