Evaluation of the inhibitory effect of amphotericin B on the apical growth of F. solani using the BioCell-Tracer system.
The BioCell-Tracer (BCT) system is an automatic microscopic method used for measuring the growth rate of a single fungal hyphae, which has not yet been applied to study Fusarium spp. Considering the large resistance of Fusarium species to the available chemotherapy and that hyphae is the morphological fungal form most often seen in vivo, in this work, Amphotericin B MIC and MFC values for a Fusarium solani strain were obtained by the conventional assay method testing conidia and also by the BCT monitoring system. Both MIC and MFC values of AMB against F. solani determined by broth dilution method resulted in 4.0 microg ml(-1). By the BCT system, their values were 1.0 microg ml(-1), with an inhibition rate of 99.5% (Exp-GR) and 100.0% (Post-GR), showing that when testing hyphae directly, MIC and MFC were determined at two lower dilutions than the MIC and MFC values obtained with conidia. Using the BCT system, 4.0, 2.0 and 1.0 microg ml(-1) of AMB concentrations inhibited hyphae growth in 50 min whereas 0.5 microg ml(-1) of AMB needed 100 min to start hyphae growth inhibition. These findings lead us to conclude that antifungal susceptibility varies between conidia and hyphae. For this strain of Fusarium solani, hyphae were more susceptible to AMB than conidia.
Teixeira
Ana Beatriz Alkmim
AB
Medical Sciences School, State University of Campinas, São Paulo, Brazil.
Moretti
Maria Luiza
ML
Machado
Helymar Costa
HC
Nishimura
Keiko
K
Taguchi
Hideaki
H
Schreiber
Angélica Zaninelli
AZ
D000666:Amphotericin B / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D005670:Fusarium / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development*; D006801:Humans; D025301:Hyphae / Q000187:drug effects* / Q000254:growth & development; D007091:Image Processing, Computer-Assisted; D008826:Microbial Sensitivity Tests / Q000295:instrumentation* / Q000379:methods* / Q000592:standards; D008853:Microscopy / Q000379:methods
D000935:Antifungal Agents; D000666:Amphotericin B