Development of a simple model for studying the effects of antifungal agents on multicellular communities of Aspergillus fumigatus

Eilidh Mowat, John Butcher, Sue Lang, Craig Williams, Gordon Ramage

Research output: Contribution to journalArticle

Abstract

Aspergillus fumigatus is an increasingly prevalent opportunistic fungal pathogen of various immunocompromised individuals. It has the ability to form filaments within the lungs, producing dense intertwined mycelial balls, which are difficult to treat. The aim of this study was to develop a suitable model of A. fumigatus to examine the effects of antifungal challenge on these intertwined filamentous communities. A. fumigatus NCPF 7367 growth conditions were optimized on both Thermanox coverslips and on flat-bottomed microtitre plates to establish optimal conidial seeding densities. Isolates were treated with itraconazole, voriconazole, amphotericin B and caspofungin and their overall killing efficiency was measured using an XTT formazan metabolic dye assay. This was compared with the CLSI (formerly NCCLS) methodology of broth microdilution of moulds (standard M38-A). It was shown that 1x10(5) conidia ml(-1) in RPMI 1640 was the optimum concentration of spores for biofilm formation. Filamentous growth characteristics were not observed until 10 h incubation, followed by an exponential increase in the biofilm biomass (hyphae and extracellular material) and cellular activity (metabolism). When susceptibility testing of biofilms was compared with that of planktonic cells by CLSI broth microdilution testing, all antifungal drugs were at least 1000 times less effective at reducing the overall metabolic activity of 90 % of the cells. Overall, this study showed that A. fumigatus has the ability to form coherent multicellular biofilm structures that are resistant to the effects of antifungal drugs.

Original languageEnglish
Pages (from-to)1205-12
Number of pages8
JournalJournal of Medical Microbiology
Volume56
Issue number9
DOIs
Publication statusPublished - Sep 2007
Externally publishedYes

Fingerprint

Aspergillus fumigatus
Antifungal Agents
Biofilms
caspofungin
Itraconazole
Fungal Spores
Hyphae
Amphotericin B
Growth
Spores
Pharmaceutical Preparations
Biomass
Fungi
Coloring Agents
Lung

Keywords

  • Antifungal Agents
  • Aspergillus fumigatus
  • Biofilms
  • Formazans
  • Hyphae
  • Microbial Sensitivity Tests
  • Microbial Viability

Cite this

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title = "Development of a simple model for studying the effects of antifungal agents on multicellular communities of Aspergillus fumigatus",
abstract = "Aspergillus fumigatus is an increasingly prevalent opportunistic fungal pathogen of various immunocompromised individuals. It has the ability to form filaments within the lungs, producing dense intertwined mycelial balls, which are difficult to treat. The aim of this study was to develop a suitable model of A. fumigatus to examine the effects of antifungal challenge on these intertwined filamentous communities. A. fumigatus NCPF 7367 growth conditions were optimized on both Thermanox coverslips and on flat-bottomed microtitre plates to establish optimal conidial seeding densities. Isolates were treated with itraconazole, voriconazole, amphotericin B and caspofungin and their overall killing efficiency was measured using an XTT formazan metabolic dye assay. This was compared with the CLSI (formerly NCCLS) methodology of broth microdilution of moulds (standard M38-A). It was shown that 1x10(5) conidia ml(-1) in RPMI 1640 was the optimum concentration of spores for biofilm formation. Filamentous growth characteristics were not observed until 10 h incubation, followed by an exponential increase in the biofilm biomass (hyphae and extracellular material) and cellular activity (metabolism). When susceptibility testing of biofilms was compared with that of planktonic cells by CLSI broth microdilution testing, all antifungal drugs were at least 1000 times less effective at reducing the overall metabolic activity of 90 {\%} of the cells. Overall, this study showed that A. fumigatus has the ability to form coherent multicellular biofilm structures that are resistant to the effects of antifungal drugs.",
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Development of a simple model for studying the effects of antifungal agents on multicellular communities of Aspergillus fumigatus. / Mowat, Eilidh; Butcher, John; Lang, Sue; Williams, Craig; Ramage, Gordon.

In: Journal of Medical Microbiology, Vol. 56, No. 9, 09.2007, p. 1205-12.

Research output: Contribution to journalArticle

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T1 - Development of a simple model for studying the effects of antifungal agents on multicellular communities of Aspergillus fumigatus

AU - Mowat, Eilidh

AU - Butcher, John

AU - Lang, Sue

AU - Williams, Craig

AU - Ramage, Gordon

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AB - Aspergillus fumigatus is an increasingly prevalent opportunistic fungal pathogen of various immunocompromised individuals. It has the ability to form filaments within the lungs, producing dense intertwined mycelial balls, which are difficult to treat. The aim of this study was to develop a suitable model of A. fumigatus to examine the effects of antifungal challenge on these intertwined filamentous communities. A. fumigatus NCPF 7367 growth conditions were optimized on both Thermanox coverslips and on flat-bottomed microtitre plates to establish optimal conidial seeding densities. Isolates were treated with itraconazole, voriconazole, amphotericin B and caspofungin and their overall killing efficiency was measured using an XTT formazan metabolic dye assay. This was compared with the CLSI (formerly NCCLS) methodology of broth microdilution of moulds (standard M38-A). It was shown that 1x10(5) conidia ml(-1) in RPMI 1640 was the optimum concentration of spores for biofilm formation. Filamentous growth characteristics were not observed until 10 h incubation, followed by an exponential increase in the biofilm biomass (hyphae and extracellular material) and cellular activity (metabolism). When susceptibility testing of biofilms was compared with that of planktonic cells by CLSI broth microdilution testing, all antifungal drugs were at least 1000 times less effective at reducing the overall metabolic activity of 90 % of the cells. Overall, this study showed that A. fumigatus has the ability to form coherent multicellular biofilm structures that are resistant to the effects of antifungal drugs.

KW - Antifungal Agents

KW - Aspergillus fumigatus

KW - Biofilms

KW - Formazans

KW - Hyphae

KW - Microbial Sensitivity Tests

KW - Microbial Viability

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DO - 10.1099/jmm.0.47247-0

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JO - Journal of Medical Microbiology

JF - Journal of Medical Microbiology

SN - 0022-2615

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