Effect of filamentation and mode of growth on antifungal susceptibility of Candida albicans.
Biofilm formation involving profuse hyphal growth is a major characteristic of Candida spp. and confers higher antifungal resistance than its planktonic mode of growth. We investigated the antifungal susceptibility of Candida albicans and its hyphal mutants (Delta efg1/efg1, Delta cph1/cph1 and DeltaDelta cph1/cph1 efg1/efg1) to commonly used antifungals during planktonic, adhesion and biofilm modes of growth. The minimum inhibitory concentration (MIC) of each antifungal agent was determined for a lower inoculum (1x10(3) cells/mL) and higher inoculum (1x10(7) cells/mL) of planktonic Candida. Furthermore, MICs of C. albicans biofilms and adhesion modes of growth were determined with a standard XTT assay. Candida albicans in adhesion and biofilm modes of growth, but not in planktonic mode, were resistant to all five antifungal agents tested. Although Delta efg1/efg1 and DeltaDelta cph1/cph1 efg1/efg1 mutants formed less biofilm than wild-type C. albicans SC5314, they were similarly resistant to caspofungin. However, these mutants were more sensitive to amphotericin B and nystatin than the wild-type. Adhesion per se confers increased resistance to antifungal agents, which is further pronounced in the biofilm mode of Candida. Filamentation does not appear to be a major determinant of the antifungal resistance in Candida biofilms.
Watamoto
T
T
Oral BioSciences, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, 34 Hospital Road, Pokfulam, Hong Kong, China.
Samaranayake
L P
LP
Jayatilake
J A M S
JA
Egusa
H
H
Yatani
H
H
Seneviratne
C J
CJ
D000935:Antifungal Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D002176:Candida albicans / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development*; D002448:Cell Adhesion; D003470:Culture Media; D025141:Drug Resistance, Fungal; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D025301:Hyphae / Q000235:genetics / Q000254:growth & development; D008826:Microbial Sensitivity Tests; D009154:Mutation; D010933:Plankton / Q000187:drug effects / Q000254:growth & development
D000935:Antifungal Agents; D003470:Culture Media; D005656:Fungal Proteins