Interactions of Trichophyton mentagrophytes and micrococci on skin culture.

Scanning electron microscopy was used to search for local or limited synthesis of antibiotics by a strain of Trichophyton mentagrophytes. Micrococcus luteus, which was susceptible to penicillin and to the dermatophyte when both were cultured on agar media, displayed morphological alterations of flattened walls, invagination, enlargement, and collapse in skin cultures with the fungus. Penicillinase did not neutralize these effects. A control strain of Staphylococcus spp with poor sensitivity to penicillin was resistant to the dermatophyte in all test systems. T. mentagrophytes showed positive tropism to the bacteria. Regional variation in fungal germination and antibiotic production, the limited yield of antibiotics, and the pattern of dermatophyte growth and alteration of bacterial morphology demonstrated the significant influence of microenvironment on antibiosis.