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Dermatophyte Viability at Modestly Raised Temperatures

Dermatophyte Viability at Modestly Raised Temperatures Abstract In approximately three-fourths of 100 strains of dermatophytes tested, exposure for two weeks to even the modest heat of 39 C not only inhibited but was apparently lethal to inocula of the organisms on Sabouraud's dextrose agar. No strain survived similar exposure to 43 C. In most cases exposure to this latter temperature for 72 hours was sufficient to prevent growth of the inocula. In Sabouraud's liquid shake culture preparations inocula of 24 strains of dermatophytes failed to grow after exposures for one week to temperatures ranging from 39 to 43 C. In many cases exposure to 43 C for only 5½ hours completely inhibited established inocula in such preparations. Such 5½ hour daily exposures for four days proved lethal to all 12 strains of dermatophytes tested in this manner. The germination of spores of Microsporum gypseum was completely inhibited by exposure to humid heating at 43 C for three days; spores of Trichophyton mentagrophytes required ten days of such exposure for similar complete inhibition of germination. A technique is described for establishing infections with M. gypseum on the tails of rats. Such infections failed to develop if the tails were kept at 41 C for one week after inoculation. Similar infections established on rat tails for one week cleared after exposure for seven to ten days to 41 C. No spontaneous tendency to heal over a period of one month was observed in the case of control M. gypseum infections on rat tails kept at room temperature. The results of these studies might suggest clinical trial of prolonged wet heat in the treatment of stubborn dermatophytic infections. There are, however, hypothetical reasons for caution in such clinical trials. References 1. Verujski, D.: Recherches sur la morphologie et la biologie du Trichophyton tonsurans et de l'Achorion schoenleinii , Ann Inst Pasteur 1:369-391, 1887. 2. Sabouraud, R.: Les teignes , Paris: Masson et Cie, 1910, pp 168-169. 3. Gabrielsen, E. K.: Studies on Trichophyton Interdigitale Priestley: I. Influence of the Temperature on the Growth of the Fungus: II. Thermoresistance of the Fungus , Acta Dermatovener (Stockh) 23:405-415, 1943. 4. Robbins, W. J., and Ma, R.: Growth Factors for Trichophyton Mentagrophytes , Amer J Bot 32: 509-523, 1945.Crossref 5. Giblett, E. R., and Henry, B. S.: Physiological Studies on the Genus Microsporum . J Invest Derm 14:377-386, 1950. 6. Stockdale, P. M.: Nutritional Requirements of the Dermatophytes , Biol Rev 28:84-104, 1953.Crossref 7. Paldrok, H.: The Effect of Temperature on the Growth and Development of Dermatophytes , Acta Dermatovener (Stockh) 35:1-30, 1955. 8. Stockdale, P. M.: Requirements for the Growth and Sporulation of Trichophyton persicolor , J Gen Microbiol 8:434-441, 1953.Crossref 9. Rippon, J. W.: "Dimorphism in Pathogenic Fungi," Dissertation for PhD degree in microbiology, University of Ill, 1959. Reproduced by University Microfilms Inc., Ann Harbor, Mich, 1961. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Dermatology American Medical Association

Dermatophyte Viability at Modestly Raised Temperatures

Archives of Dermatology , Volume 88 (4) – Oct 1, 1963

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Publisher
American Medical Association
Copyright
Copyright © 1963 American Medical Association. All Rights Reserved.
ISSN
0003-987X
eISSN
1538-3652
DOI
10.1001/archderm.1963.01590220025003
Publisher site
See Article on Publisher Site

Abstract

Abstract In approximately three-fourths of 100 strains of dermatophytes tested, exposure for two weeks to even the modest heat of 39 C not only inhibited but was apparently lethal to inocula of the organisms on Sabouraud's dextrose agar. No strain survived similar exposure to 43 C. In most cases exposure to this latter temperature for 72 hours was sufficient to prevent growth of the inocula. In Sabouraud's liquid shake culture preparations inocula of 24 strains of dermatophytes failed to grow after exposures for one week to temperatures ranging from 39 to 43 C. In many cases exposure to 43 C for only 5½ hours completely inhibited established inocula in such preparations. Such 5½ hour daily exposures for four days proved lethal to all 12 strains of dermatophytes tested in this manner. The germination of spores of Microsporum gypseum was completely inhibited by exposure to humid heating at 43 C for three days; spores of Trichophyton mentagrophytes required ten days of such exposure for similar complete inhibition of germination. A technique is described for establishing infections with M. gypseum on the tails of rats. Such infections failed to develop if the tails were kept at 41 C for one week after inoculation. Similar infections established on rat tails for one week cleared after exposure for seven to ten days to 41 C. No spontaneous tendency to heal over a period of one month was observed in the case of control M. gypseum infections on rat tails kept at room temperature. The results of these studies might suggest clinical trial of prolonged wet heat in the treatment of stubborn dermatophytic infections. There are, however, hypothetical reasons for caution in such clinical trials. References 1. Verujski, D.: Recherches sur la morphologie et la biologie du Trichophyton tonsurans et de l'Achorion schoenleinii , Ann Inst Pasteur 1:369-391, 1887. 2. Sabouraud, R.: Les teignes , Paris: Masson et Cie, 1910, pp 168-169. 3. Gabrielsen, E. K.: Studies on Trichophyton Interdigitale Priestley: I. Influence of the Temperature on the Growth of the Fungus: II. Thermoresistance of the Fungus , Acta Dermatovener (Stockh) 23:405-415, 1943. 4. Robbins, W. J., and Ma, R.: Growth Factors for Trichophyton Mentagrophytes , Amer J Bot 32: 509-523, 1945.Crossref 5. Giblett, E. R., and Henry, B. S.: Physiological Studies on the Genus Microsporum . J Invest Derm 14:377-386, 1950. 6. Stockdale, P. M.: Nutritional Requirements of the Dermatophytes , Biol Rev 28:84-104, 1953.Crossref 7. Paldrok, H.: The Effect of Temperature on the Growth and Development of Dermatophytes , Acta Dermatovener (Stockh) 35:1-30, 1955. 8. Stockdale, P. M.: Requirements for the Growth and Sporulation of Trichophyton persicolor , J Gen Microbiol 8:434-441, 1953.Crossref 9. Rippon, J. W.: "Dimorphism in Pathogenic Fungi," Dissertation for PhD degree in microbiology, University of Ill, 1959. Reproduced by University Microfilms Inc., Ann Harbor, Mich, 1961.

Journal

Archives of DermatologyAmerican Medical Association

Published: Oct 1, 1963

References