Dermatophyte Lesions in the Hedgehog as a Reservoir of Penicillin Resistant Staphylococci.

An antibiotic substance biologically resembling penicillin G was produced by the growth of Trichophyton mentagrophytes var. erinacei, T. mentagrophytes var. granulare and T. mentagrophytes var. interdigitale in Sabouraud's dextrose broth. An antibiotic concentration equivalent to 7 units/ml. penicillin G could be produced by var. erinacei when grown in a suitable nutrient medium. Epidermophyton floccosum also produced a substance which inhibited the growth of the Oxford staphylococcus. However, this substance was not completely inactivated by penicillinase. No in vitro antibiotic production could be demonstrated with T. rubrum, T. concentricum, T. terrestre or Microsporum canis . Penicillin production could be demonstrated in rabbit skin infected with T. ment-agrophytes var. erinacei. Pathogenic staphylococci falling on a var. erinacei guinea-pig lesion increased rapidly in the ringworm tissue. The inhibiting concentration of penicillin G for such staphylococci was shown to increase from 5·0 µg./ml. to above 20·0 µg./ml. as the ringworm progressed. The presence of T. mentagrophytes var. erinacei in a high percentage of hedgehogs is considered the main reason why the skin is the primary site of staphylococcal multiplication in hedgehogs and why most of the Staphylococcias aureus strains recoverable from these animals are penicillin resistant.