JAC Advance Access originally published online on March 16, 2005
Journal of Antimicrobial Chemotherapy 2005 55(5):692-698; doi:10.1093/jac/dki084
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In vitro activity of 2-cyclohexylidenhydrazo-4-phenyl-thiazole compared with those of amphotericin B and fluconazole against clinical isolates of Candida spp. and fluconazole-resistant Candida albicans
1 Dipartimento di Scienze e Tecnologie Biomediche, Sezione di Microbiologia Medica, 2 Facoltà di Farmacia, and 3 Dipartimento Farmaco Chimico Tecnologico, Università di Cagliari, Cagliari, Italy; 4 Ospedale SS. Trinità, Cagliari, Italy
* Correspondence address. Sezione di Microbiologia Medica, Dipartimento di Scienze e Tecnologie Biomediche, Università di Cagliari, Viale Sant'Ignazio, 3809123 Cagliari, Italy. Tel: +39-070-651583; Fax: +39-070-659255; Email: adelogu{at}unica.it
Objectives: The aim of this study was to investigate the in vitro antifungal activity of an isothiosemicarbazone cyclic analogue against isolates of Candida spp. including fluconazole-resistant Candida albicans.
Methods: We investigated the activity of 2-cyclohexylidenhydrazo-4-phenyl-thiazole (EM-01D2) against 114 clinical isolates of Candida spp., representing five different species, by microdilution, according to the NCCLS method 27-A. The activity against C. albicans biofilms was also investigated. Toxicity in vitro was evaluated by MTT reduction assay.
Results: EM-01D2 demonstrated low toxicity, broad spectrum, fungicidal activity and was active against C. albicans and Candida krusei at concentrations lower than those shown by amphotericin B and fluconazole (P < 0.05). It maintained potent in vitro activity against fluconazole-resistant C. albicans isolates. Fungicidal activity occurred at concentrations 12 doubling dilutions greater than the corresponding MICs, and timekill analysis indicated that a 99.9% loss of C. albicans viability occurred after 6 h of incubation in the presence of EM-01D2 at concentrations equal to four times the MIC. EM-01D2 was also active in inhibiting the growth of C. albicans ATCC 10231 biofilms, even though such inhibition occurred at concentrations higher than the MICs determined under planktonic growth conditions. However, when C. albicans biofilms were pre-exposed to subinhibitory concentrations of EM-01D2, a reduction of MIC50 of amphotericin B was observed.
Conclusions: Based on these results, EM-01D2 could represent a template for the development of novel fungicidal agents.
Keywords: antifungal agents , biofilms , isothiosemicarbazone derivatives