[Evaluation and utility of the E-test and Neo-Sensitabs methods in studying fluconazole yeast susceptibility].
Standardized broth dilution methods are cumbersome for routine use in a clinical laboratory to study antifungal yeast susceptibility. Recently, the CLSI has standardized a disk diffusion method faster and more suitable to study fluconazole and voriconazole susceptibility. The objectives of the present study were to determine: a) the suitability of the Neo-Sensitabs tablets to study fluconazole susceptibility; b) whether Mueller-Hinton agar with methylene blue (MHAG-AM) could be used in the E-test method; and c) the interaction of the methylene blue with RPMI medium. A total of 84 blood stream yeast isolates were used (25 C. albicans, 7 C. parapsilosis, 10 C. tropicalis, 12 C. glabrata, 7 C. krusei, 4 C. lusitaniae and 19 C. neoformans). The methylene blue makes sharper inhibition zones both in MHAG-AM and RPMI media. With fluconazole Neo-Sensitabs tablets, the lowest percentage of very major errors was found in MHAG-AM and the greatest in RPMIG. In both diffusion methods and culture media, the very major errors were found in C. albicans, C. tropicalis (only with Neo-Sensitabs) and C. glabrata. The percentage of fluconazole-resistant strains was lower in the media that contained glucose (2%). Neo-Sensitabs tablets are a reliable alternative to the dilution methods to detect fluconazole susceptibility. In the case of resistance, more studies are required; nevertheless, inhibition zone > or =17 mm should be applied to define fluconazole resistance.
Cantón
E
E
Unidad de Microbiologia Experimental del Centro de Investigacion, Hospital Universitario La Fe, Valencia, Spain.
Pemán
J
J
Sastre
M
M
Valentín
A
A
Bosch
M
M
Espinel-Ingroff
A
A
D000935:Antifungal Agents / Q000494:pharmacology*; D002175:Candida / Q000187:drug effects*; D002177:Candidiasis / Q000188:drug therapy; D003453:Cryptococcosis / Q000188:drug therapy; D003455:Cryptococcus neoformans / Q000187:drug effects*; D052978:Disk Diffusion Antimicrobial Tests / Q000295:instrumentation* / Q000379:methods; D025141:Drug Resistance, Fungal; D015725:Fluconazole / Q000494:pharmacology*; D006801:Humans
D000935:Antifungal Agents; D015725:Fluconazole