Isolation of Dermatophytes from House Dust

Chung, Kyung Jae; Jun, Jae Bok

Abstract

BACKGROUND
Dermatophytosis is usually caused by a contact of the skin with the infective particles in the environment.
OBJECTIVE
To investigate the extent and severity of environmental contamination by dermatophytes. METHOD: In addition to physical examination on the residents of 46 families in a rural town in Kyungpook Province, clinical material and house dust samples were cultivated for dermatophytes.
RESULTS
Among 114 persons from the 46 families, dermatophytosis was detected in 33 persons(28.9%). The most frequent clinical type was tinea pedis. Trichophyton rubrum and T. mentagrophytes were etiologic agents. In 22 families (47.8%), T. rubrum (16 families, 34.8%) and T. mentagrophytes (6 families, 13.0%) were isolated from the skin lesions. The remaining 24 families (52.2%) were free from dermatophytosis. T. rubrum was detected in the house dust samples from 40(86.9%) of the 46 families, with a density of 34.0 colonies/g, the highest among isolates.; T. mentagrophytes, from 32(69.6%); Microsporum canis, from 1(0.2%); 3(6.5%) were without any dermatophytes. T. rubrum was isolated from the house dust of 15(93.7%) out of 16 families having tinea patients infected with the same fungus, and T. mentagrophytes in 5(83.3%) out of 6. Each case was frequently detected together with other dermatophytes. T. mentagrophytes subtypes were isolated from house dust singly in 19(41.3%), and in twos and threes in 13(28.3%) of the 46 families. Even in the families of the patient(s) with the fungus, the subtypes were not always identical with those from house dust. In a mating study with a total of 210 strains of T. mentagrophytes, 130 out of 136 (including 6 indeterminate) strains of granulosum-asteroides form turned out to be Arthroderma vanbreuseghemii " - ". But all the 70 strains of the powdery, persicolor and downy forms that showed strong sexual stimulation by tester strains, were "+".
CONCLUSION
House dust was extensively and markedly contaminated by dermatophytes in a rural town. Further study is needed to evaluate the distribution of mating types of the members of T. mentagrophytes complex in a clinical setting.