A comparative study of fungicidal activities of voriconazole and amphotericin B against hyphae of Aspergillus fumigatus

Suganthini Krishnan, Elias Kurian Manavathu, Pranatharthi H. Chandrasekar

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Objectives: To study the in vitro fungicidal activity of voriconazole against hyphae of Aspergillus fumigatus and compare the results with those obtained for the known fungicidal drug amphotericin B. Methods: A. fumigatus mycelia were grown on Sabouraud dextrose agar and in peptone yeast extract glucose broth until the cultures reached a mid-logarithmic growth phase. The fungicidal activities of voriconazole and amphotericin B against actively growing hyphae of A. fumigatus were examined by a kill-curve experiment and a fungal cell viability test. For the kill-curve study, the drug-treated hyphae were washed, homogenized and resuspended in 1 mL of sterile water, diluted 10-1000 fold and aliquots of 0.1 mL were spread on Sabouraud dextrose agar and allowed to grow for 48 h at 35°C. The cfu were determined and plotted against drug concentrations for each time of exposure to obtain the kill curve. The viability of drug-treated A. fumigatus hyphae was determined by their ability to reduce tetrazolium compound 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide. Results: Exposure of A. fumigatus hyphae to several concentrations (1-16mg/L) of voriconazole or amphotericin B for various time intervals killed the hyphae in a time- and drug concentration-dependent manner. Voriconazole at 1 mg/L killed >95% of the hyphae grown on Sabouraud dextrose agar after 48h of exposure, whereas amphotericin B at the same concentration killed ∼70% of the hyphae after exposure for the same duration. Approximately 99% killing of hyphae grown in peptone yeast extract glucose broth was obtained for voriconazole at 1 mg/L after 48 h of exposure, whereas amphotericin B at 1 mg/L yielded ∼82% killing after 48h. The fungal cell viability test by tetrazolium reduction assay showed that mycelia exposed to ≥1 mg/L (Sabouraud dextrose agar blocks) and ≥2 mg/L (broth cultures) of voriconazole for 48h completely failed to reduce 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide. At low concentrations (1-2 mg/L) amphotericin B had no detectable effect on 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide reduction by drug-treated mycelia, whereas mycelia treated with 16 mg/L for 48h showed ∼50% inhibition of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide reduction compared with the control. Conclusions: Voriconazole possesses excellent fungicidal activity against actively growing hyphae of A. fumigatus. A comparison of results with those obtained for the known fungicidal drug amphotericin B shows that, in peptone yeast extract glucose broth, voriconazole has superior fungicidal activity against A. fumigatus hyphae compared with that of amphotericin B.

Original languageEnglish (US)
Pages (from-to)914-920
Number of pages7
JournalJournal of Antimicrobial Chemotherapy
Volume55
Issue number6
DOIs
StatePublished - Jun 1 2005

Fingerprint

Aspergillus fumigatus
Hyphae
Amphotericin B
Glucose
Mycelium
Peptones
Agar
Pharmaceutical Preparations
Yeasts
Cell Survival
Voriconazole

Keywords

  • Aspergillus fumigatus
  • Fungal hyphae
  • Fungicidal activity
  • Kill curve
  • Viability test
  • Voriconazole

ASJC Scopus subject areas

  • Pharmacology
  • Microbiology

Cite this

A comparative study of fungicidal activities of voriconazole and amphotericin B against hyphae of Aspergillus fumigatus. / Krishnan, Suganthini; Manavathu, Elias Kurian; Chandrasekar, Pranatharthi H.

In: Journal of Antimicrobial Chemotherapy, Vol. 55, No. 6, 01.06.2005, p. 914-920.

Research output: Contribution to journalArticle

Krishnan, Suganthini ; Manavathu, Elias Kurian ; Chandrasekar, Pranatharthi H. / A comparative study of fungicidal activities of voriconazole and amphotericin B against hyphae of Aspergillus fumigatus. In: Journal of Antimicrobial Chemotherapy. 2005 ; Vol. 55, No. 6. pp. 914-920.
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abstract = "Objectives: To study the in vitro fungicidal activity of voriconazole against hyphae of Aspergillus fumigatus and compare the results with those obtained for the known fungicidal drug amphotericin B. Methods: A. fumigatus mycelia were grown on Sabouraud dextrose agar and in peptone yeast extract glucose broth until the cultures reached a mid-logarithmic growth phase. The fungicidal activities of voriconazole and amphotericin B against actively growing hyphae of A. fumigatus were examined by a kill-curve experiment and a fungal cell viability test. For the kill-curve study, the drug-treated hyphae were washed, homogenized and resuspended in 1 mL of sterile water, diluted 10-1000 fold and aliquots of 0.1 mL were spread on Sabouraud dextrose agar and allowed to grow for 48 h at 35°C. The cfu were determined and plotted against drug concentrations for each time of exposure to obtain the kill curve. The viability of drug-treated A. fumigatus hyphae was determined by their ability to reduce tetrazolium compound 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide. Results: Exposure of A. fumigatus hyphae to several concentrations (1-16mg/L) of voriconazole or amphotericin B for various time intervals killed the hyphae in a time- and drug concentration-dependent manner. Voriconazole at 1 mg/L killed >95{\%} of the hyphae grown on Sabouraud dextrose agar after 48h of exposure, whereas amphotericin B at the same concentration killed ∼70{\%} of the hyphae after exposure for the same duration. Approximately 99{\%} killing of hyphae grown in peptone yeast extract glucose broth was obtained for voriconazole at 1 mg/L after 48 h of exposure, whereas amphotericin B at 1 mg/L yielded ∼82{\%} killing after 48h. The fungal cell viability test by tetrazolium reduction assay showed that mycelia exposed to ≥1 mg/L (Sabouraud dextrose agar blocks) and ≥2 mg/L (broth cultures) of voriconazole for 48h completely failed to reduce 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide. At low concentrations (1-2 mg/L) amphotericin B had no detectable effect on 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide reduction by drug-treated mycelia, whereas mycelia treated with 16 mg/L for 48h showed ∼50{\%} inhibition of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide reduction compared with the control. Conclusions: Voriconazole possesses excellent fungicidal activity against actively growing hyphae of A. fumigatus. A comparison of results with those obtained for the known fungicidal drug amphotericin B shows that, in peptone yeast extract glucose broth, voriconazole has superior fungicidal activity against A. fumigatus hyphae compared with that of amphotericin B.",
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TY - JOUR

T1 - A comparative study of fungicidal activities of voriconazole and amphotericin B against hyphae of Aspergillus fumigatus

AU - Krishnan, Suganthini

AU - Manavathu, Elias Kurian

AU - Chandrasekar, Pranatharthi H.

PY - 2005/6/1

Y1 - 2005/6/1

N2 - Objectives: To study the in vitro fungicidal activity of voriconazole against hyphae of Aspergillus fumigatus and compare the results with those obtained for the known fungicidal drug amphotericin B. Methods: A. fumigatus mycelia were grown on Sabouraud dextrose agar and in peptone yeast extract glucose broth until the cultures reached a mid-logarithmic growth phase. The fungicidal activities of voriconazole and amphotericin B against actively growing hyphae of A. fumigatus were examined by a kill-curve experiment and a fungal cell viability test. For the kill-curve study, the drug-treated hyphae were washed, homogenized and resuspended in 1 mL of sterile water, diluted 10-1000 fold and aliquots of 0.1 mL were spread on Sabouraud dextrose agar and allowed to grow for 48 h at 35°C. The cfu were determined and plotted against drug concentrations for each time of exposure to obtain the kill curve. The viability of drug-treated A. fumigatus hyphae was determined by their ability to reduce tetrazolium compound 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide. Results: Exposure of A. fumigatus hyphae to several concentrations (1-16mg/L) of voriconazole or amphotericin B for various time intervals killed the hyphae in a time- and drug concentration-dependent manner. Voriconazole at 1 mg/L killed >95% of the hyphae grown on Sabouraud dextrose agar after 48h of exposure, whereas amphotericin B at the same concentration killed ∼70% of the hyphae after exposure for the same duration. Approximately 99% killing of hyphae grown in peptone yeast extract glucose broth was obtained for voriconazole at 1 mg/L after 48 h of exposure, whereas amphotericin B at 1 mg/L yielded ∼82% killing after 48h. The fungal cell viability test by tetrazolium reduction assay showed that mycelia exposed to ≥1 mg/L (Sabouraud dextrose agar blocks) and ≥2 mg/L (broth cultures) of voriconazole for 48h completely failed to reduce 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide. At low concentrations (1-2 mg/L) amphotericin B had no detectable effect on 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide reduction by drug-treated mycelia, whereas mycelia treated with 16 mg/L for 48h showed ∼50% inhibition of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide reduction compared with the control. Conclusions: Voriconazole possesses excellent fungicidal activity against actively growing hyphae of A. fumigatus. A comparison of results with those obtained for the known fungicidal drug amphotericin B shows that, in peptone yeast extract glucose broth, voriconazole has superior fungicidal activity against A. fumigatus hyphae compared with that of amphotericin B.

AB - Objectives: To study the in vitro fungicidal activity of voriconazole against hyphae of Aspergillus fumigatus and compare the results with those obtained for the known fungicidal drug amphotericin B. Methods: A. fumigatus mycelia were grown on Sabouraud dextrose agar and in peptone yeast extract glucose broth until the cultures reached a mid-logarithmic growth phase. The fungicidal activities of voriconazole and amphotericin B against actively growing hyphae of A. fumigatus were examined by a kill-curve experiment and a fungal cell viability test. For the kill-curve study, the drug-treated hyphae were washed, homogenized and resuspended in 1 mL of sterile water, diluted 10-1000 fold and aliquots of 0.1 mL were spread on Sabouraud dextrose agar and allowed to grow for 48 h at 35°C. The cfu were determined and plotted against drug concentrations for each time of exposure to obtain the kill curve. The viability of drug-treated A. fumigatus hyphae was determined by their ability to reduce tetrazolium compound 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide. Results: Exposure of A. fumigatus hyphae to several concentrations (1-16mg/L) of voriconazole or amphotericin B for various time intervals killed the hyphae in a time- and drug concentration-dependent manner. Voriconazole at 1 mg/L killed >95% of the hyphae grown on Sabouraud dextrose agar after 48h of exposure, whereas amphotericin B at the same concentration killed ∼70% of the hyphae after exposure for the same duration. Approximately 99% killing of hyphae grown in peptone yeast extract glucose broth was obtained for voriconazole at 1 mg/L after 48 h of exposure, whereas amphotericin B at 1 mg/L yielded ∼82% killing after 48h. The fungal cell viability test by tetrazolium reduction assay showed that mycelia exposed to ≥1 mg/L (Sabouraud dextrose agar blocks) and ≥2 mg/L (broth cultures) of voriconazole for 48h completely failed to reduce 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide. At low concentrations (1-2 mg/L) amphotericin B had no detectable effect on 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide reduction by drug-treated mycelia, whereas mycelia treated with 16 mg/L for 48h showed ∼50% inhibition of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide reduction compared with the control. Conclusions: Voriconazole possesses excellent fungicidal activity against actively growing hyphae of A. fumigatus. A comparison of results with those obtained for the known fungicidal drug amphotericin B shows that, in peptone yeast extract glucose broth, voriconazole has superior fungicidal activity against A. fumigatus hyphae compared with that of amphotericin B.

KW - Aspergillus fumigatus

KW - Fungal hyphae

KW - Fungicidal activity

KW - Kill curve

KW - Viability test

KW - Voriconazole

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