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.
OBJECTIVE
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 1-2 doubling dilutions greater than the corresponding MICs, and time-kill 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.
De Logu
Alessandro
A
Dipartimento di Scienze e Tecnologie Biomediche, Sezione di Microbiologia Medica, Università di Cagliari, Cagliari, Italy. adelogu@unica.it
Saddi
Manuela
M
Cardia
Maria Cristina
MC
Borgna
Rita
R
Sanna
Clara
C
Saddi
Barbara
B
Maccioni
Elias
E
D000666:Amphotericin B / Q000494:pharmacology*; D000818:Animals; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D002175:Candida / Q000145:classification / Q000187:drug effects*; D002176:Candida albicans / Q000187:drug effects / Q000254:growth & development; D002522:Chlorocebus aethiops; D025141:Drug Resistance, Fungal; D015725:Fluconazole / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D013882:Thiosemicarbazones / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D014709:Vero Cells
D000935:Antifungal Agents; D013882:Thiosemicarbazones; D000666:Amphotericin B; D015725:Fluconazole