Azole resistance of Aspergillus fumigatus biofilms is partly associated with efflux pump activity

Ranjith Rajendran, Eilidh Mowat, Elaine McCulloch, David F Lappin, Brian L. Jones, Sue Lang, Jayesh B Majithiya, Peter Warn, Craig Williams, Gordon Ramage

Research output: Contribution to journalArticle

Abstract

This study investigated the phase-dependent expression and activity of efflux pumps in Aspergillus fumigatus treated with voriconazole. Fourteen strains were shown to become increasingly resistant in the 12-h (16- to 128-fold) and 24-h (>512-fold) phases compared to 8-h germlings. An Ala-Nap uptake assay demonstrated a significant increase in efflux pump activity in the 12-h and 24-h phases (P<0.0001). The efflux pump activity of the 8-h germling cells was also significantly induced by voriconazole (P<0.001) after 24 h of treatment. Inhibition of efflux pump activity with the competitive substrate MC-207,110 reduced the voriconazole MIC values for the A. fumigatus germling cells by 2- to 8-fold. Quantitative expression analysis of AfuMDR4 mRNA transcripts showed a phase-dependent increase as the mycelial complexity increased, which was coincidental with a strain-dependent increase in azole resistance. Voriconazole also significantly induced this in a time-dependent manner (P<0.001). Finally, an in vivo mouse biofilm model was used to evaluate efflux pump expression, and it was shown that AfuMDR4 was constitutively expressed and significantly induced by treatment with voriconazole after 24 h (P<0.01). Our results demonstrate that efflux pumps are expressed in complex A. fumigatus biofilm populations and that this contributes to azole resistance. Moreover, voriconazole treatment induces efflux pump expression. Collectively, these data may provide evidence for azole treatment failures in clinical cases of aspergillosis.

Original languageEnglish
Pages (from-to)2092-2097
Number of pages6
JournalAntimicrobial Agents and Chemotherapy
Volume55
Issue number5
DOIs
Publication statusPublished - 1 May 2011
Externally publishedYes

Fingerprint

Azoles
Aspergillus fumigatus
Biofilms
Aspergillosis
Treatment Failure
Voriconazole
Messenger RNA
Population

Keywords

  • Animals
  • Antifungal Agents
  • Aspergillosis
  • Aspergillus fumigatus
  • Azoles
  • Biofilms
  • Drug Resistance, Fungal
  • Fungal Proteins
  • Male
  • Mice
  • Microbial Sensitivity Tests
  • Pyrimidines
  • Triazoles
  • Voriconazole
  • Journal Article
  • Research Support, Non-U.S. Gov't

Cite this

Rajendran, R., Mowat, E., McCulloch, E., Lappin, D. F., Jones, B. L., Lang, S., ... Ramage, G. (2011). Azole resistance of Aspergillus fumigatus biofilms is partly associated with efflux pump activity. Antimicrobial Agents and Chemotherapy, 55(5), 2092-2097. https://doi.org/10.1128/AAC.01189-10
Rajendran, Ranjith ; Mowat, Eilidh ; McCulloch, Elaine ; Lappin, David F ; Jones, Brian L. ; Lang, Sue ; Majithiya, Jayesh B ; Warn, Peter ; Williams, Craig ; Ramage, Gordon. / Azole resistance of Aspergillus fumigatus biofilms is partly associated with efflux pump activity. In: Antimicrobial Agents and Chemotherapy. 2011 ; Vol. 55, No. 5. pp. 2092-2097.
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Rajendran, R, Mowat, E, McCulloch, E, Lappin, DF, Jones, BL, Lang, S, Majithiya, JB, Warn, P, Williams, C & Ramage, G 2011, 'Azole resistance of Aspergillus fumigatus biofilms is partly associated with efflux pump activity' Antimicrobial Agents and Chemotherapy, vol. 55, no. 5, pp. 2092-2097. https://doi.org/10.1128/AAC.01189-10

Azole resistance of Aspergillus fumigatus biofilms is partly associated with efflux pump activity. / Rajendran, Ranjith; Mowat, Eilidh; McCulloch, Elaine; Lappin, David F; Jones, Brian L. ; Lang, Sue; Majithiya, Jayesh B; Warn, Peter; Williams, Craig; Ramage, Gordon.

In: Antimicrobial Agents and Chemotherapy, Vol. 55, No. 5, 01.05.2011, p. 2092-2097.

Research output: Contribution to journalArticle

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AU - Rajendran, Ranjith

AU - Mowat, Eilidh

AU - McCulloch, Elaine

AU - Lappin, David F

AU - Jones, Brian L.

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AU - Majithiya, Jayesh B

AU - Warn, Peter

AU - Williams, Craig

AU - Ramage, Gordon

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AB - This study investigated the phase-dependent expression and activity of efflux pumps in Aspergillus fumigatus treated with voriconazole. Fourteen strains were shown to become increasingly resistant in the 12-h (16- to 128-fold) and 24-h (>512-fold) phases compared to 8-h germlings. An Ala-Nap uptake assay demonstrated a significant increase in efflux pump activity in the 12-h and 24-h phases (P<0.0001). The efflux pump activity of the 8-h germling cells was also significantly induced by voriconazole (P<0.001) after 24 h of treatment. Inhibition of efflux pump activity with the competitive substrate MC-207,110 reduced the voriconazole MIC values for the A. fumigatus germling cells by 2- to 8-fold. Quantitative expression analysis of AfuMDR4 mRNA transcripts showed a phase-dependent increase as the mycelial complexity increased, which was coincidental with a strain-dependent increase in azole resistance. Voriconazole also significantly induced this in a time-dependent manner (P<0.001). Finally, an in vivo mouse biofilm model was used to evaluate efflux pump expression, and it was shown that AfuMDR4 was constitutively expressed and significantly induced by treatment with voriconazole after 24 h (P<0.01). Our results demonstrate that efflux pumps are expressed in complex A. fumigatus biofilm populations and that this contributes to azole resistance. Moreover, voriconazole treatment induces efflux pump expression. Collectively, these data may provide evidence for azole treatment failures in clinical cases of aspergillosis.

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KW - Aspergillosis

KW - Aspergillus fumigatus

KW - Azoles

KW - Biofilms

KW - Drug Resistance, Fungal

KW - Fungal Proteins

KW - Male

KW - Mice

KW - Microbial Sensitivity Tests

KW - Pyrimidines

KW - Triazoles

KW - Voriconazole

KW - Journal Article

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EP - 2097

JO - Antimicrobial Agents and Chemotherapy

JF - Antimicrobial Agents and Chemotherapy

SN - 0066-4804

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