Affiliation:
1. Division of Infection and Immunity, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, United Kingdom
Abstract
ABSTRACT
A filter disk assay was used to investigate the penetration of antifungal agents through biofilms containing single and mixed-species biofilms containing
Candida
. Fluconazole permeated all single-species
Candida
biofilms more rapidly than flucytosine. The rates of diffusion of either drug through biofilms of three strains of
Candida albicans
were similar. However, the rates of drug diffusion through biofilms of
C. glabrata
or
C. krusei
were faster than those through biofilms of
C. parapsilosis
or
C. tropicalis
. In all cases, after 3 to 6 h the drug concentration at the distal edge of the biofilm was very high (many times the MIC). Nevertheless, drug penetration failed to produce complete killing of biofilm cells. These results indicate that poor antifungal penetration is not a major drug resistance mechanism for
Candida
biofilms. The abilities of flucytosine, fluconazole, amphotericin B, and voriconazole to penetrate mixed-species biofilms containing
C. albicans
and
Staphylococcus epidermidis
(a slime-producing wild-type strain, RP62A, and a slime-negative mutant, M7) were also investigated. All four antifungal agents diffused very slowly through these mixed-species biofilms. In most cases, diffusion was slower with biofilms containing
S. epidermidis
RP62A, but amphotericin B penetrated biofilms containing the M7 mutant more slowly. However, the drug concentrations reaching the distal edges of the biofilms always substantially exceeded the MIC. Thus, although the presence of bacteria and bacterial matrix material undoubtedly retarded the diffusion of the antifungal agents, poor penetration does not account for the drug resistance of
Candida
biofilm cells, even in these mixed-species biofilms.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Cited by
197 articles.
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