Melanization and morphological effects on antifungal susceptibility of Penicillium marneffei

Jutikul Kaewmalakul, Joshua D. Nosanchuk, Nongnuch Vanittanakom, Sirida Youngchim

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The biosynthesis of melanin has been linked with virulence in diverse pathogenic fungi. Penicillium marneffei, a dimorphic fungus, is capable of melanization in both mycelial and yeast phases, and the pigment may be produced during infection to protect the fungus from the host immune system. To investigate the impact of yeast morphological transformation on antifungal susceptibility, P. marneffei was cultured on various media including minimal medium, 1 % tryptone, brain heart infusion broth, and malt extract broth by using the standardized susceptibility protocol (the M27-A protocol, RPMI medium) for yeasts. We also investigated whether P. marneffei melanization affected its susceptibility to antifungal drugs by adding l-DOPA into culture broths. There were no differences in the minimum inhibitory concentrations of P. marneffei yeast cells previously grown in various culture broths with or without l-DOPA using the M27A protocol (into which no melanin substrate can be added due to a rapid colour change of the RPMI medium to black) for testing amphotericin B, clotrimazole, fluconazole, itraconazole and ketoconazole. However, both melanized and non-melanized P. marneffei displayed increased resistance to antifungal drugs when l-DOPA was added into a selected assay medium, 0.17 % yeast nitrogen base, 2 % glucose, and 1.5 % agar. Hence, active melanin formation appears to protect P. marneffei by enhancing its resistance to antifungal drugs.

Original languageEnglish (US)
Pages (from-to)1011-1020
Number of pages10
JournalAntonie van Leeuwenhoek, International Journal of General and Molecular Microbiology
Volume106
Issue number5
DOIs
StatePublished - Oct 7 2014

Fingerprint

Penicillium
Yeasts
Melanins
Fungal Drug Resistance
Fungi
Clotrimazole
Ketoconazole
Itraconazole
Fluconazole
Microbial Sensitivity Tests
Amphotericin B
Agar
Virulence
Immune System
Nitrogen
Color
Glucose
Brain
Infection
Pharmaceutical Preparations

Keywords

  • Antifungal susceptibility test
  • l-3,4-dihydroxyphenylalanine (l-DOPA)
  • Melanin
  • MIC
  • Penicillium marneffei

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology
  • Medicine(all)

Cite this

Melanization and morphological effects on antifungal susceptibility of Penicillium marneffei. / Kaewmalakul, Jutikul; Nosanchuk, Joshua D.; Vanittanakom, Nongnuch; Youngchim, Sirida.

In: Antonie van Leeuwenhoek, International Journal of General and Molecular Microbiology, Vol. 106, No. 5, 07.10.2014, p. 1011-1020.

Research output: Contribution to journalArticle

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abstract = "The biosynthesis of melanin has been linked with virulence in diverse pathogenic fungi. Penicillium marneffei, a dimorphic fungus, is capable of melanization in both mycelial and yeast phases, and the pigment may be produced during infection to protect the fungus from the host immune system. To investigate the impact of yeast morphological transformation on antifungal susceptibility, P. marneffei was cultured on various media including minimal medium, 1 {\%} tryptone, brain heart infusion broth, and malt extract broth by using the standardized susceptibility protocol (the M27-A protocol, RPMI medium) for yeasts. We also investigated whether P. marneffei melanization affected its susceptibility to antifungal drugs by adding l-DOPA into culture broths. There were no differences in the minimum inhibitory concentrations of P. marneffei yeast cells previously grown in various culture broths with or without l-DOPA using the M27A protocol (into which no melanin substrate can be added due to a rapid colour change of the RPMI medium to black) for testing amphotericin B, clotrimazole, fluconazole, itraconazole and ketoconazole. However, both melanized and non-melanized P. marneffei displayed increased resistance to antifungal drugs when l-DOPA was added into a selected assay medium, 0.17 {\%} yeast nitrogen base, 2 {\%} glucose, and 1.5 {\%} agar. Hence, active melanin formation appears to protect P. marneffei by enhancing its resistance to antifungal drugs.",
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