Comparative study of disc diffusion and microdilution methods in susceptibility testing of micafungin against Candida species.
OBJECTIVE
To compare the Clinical Laboratory Standards Institute CLSI M44-A disc diffusion (DD) and M27-A2 broth microdilution (MD) methods for determining the susceptibility of Candida spp. to micafungin (FK463).


METHODS
A total of 355 clinical yeast isolates including 270 Candida albicans, 45 Candida glabrata, 24 Candida krusei, 11 Candida tropicalis and 5 Candida parapsilosis were studied. The MIC of micafungin was determined by following the CLSI M27-A2 guidelines (MD). Endpoints were defined as the lowest concentration of micafungin resulting in partial inhibition (IC(50)) of visual growth after 24/48 h of incubation at 35 degrees C. Final concentrations were 0.008-4 mg/L of micafungin. DD testing was performed using a CLSI M44-A document with 2.5 mug micafungin discs. Zone diameter endpoints were read after 24/48 h of incubation at 35 degrees C. Arbitrary breakpoints were 4 mg/L for MD and 15 mm for DD.


RESULTS
The best correlation was observed when we read MD 48 h/DD 24 and 48 h (97%). When the reading was MD 24 h/DD 24 and 48 h the percentage of correlation was 95.2%.


CONCLUSIONS
The DD method performs well for testing the susceptibility of Candida spp. to micafungin. More studies involving more Candida strains with elevated MIC values are needed.
Ramírez
M
M
Servicio de Microbiología Clínica, Hospital Universitario de Valme Seville 41014, Spain.
Serrano
M C
MC
Castro
C
C
López
E
E
Almeida
C
C
Fernández
A
A
Romero
A
A
Martín-Mazuelos
E
E
D017088:AIDS-Related Opportunistic Infections / Q000382:microbiology; D000935:Antifungal Agents / Q000494:pharmacology*; D002175:Candida / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D002176:Candida albicans / Q000187:drug effects; D002180:Candidiasis, Oral / Q000382:microbiology; D003470:Culture Media; D025141:Drug Resistance, Fungal; D054714:Echinocandins; D015658:HIV Infections / Q000150:complications; D006801:Humans; D055666:Lipopeptides; D008074:Lipoproteins / Q000494:pharmacology*; D000077551:Micafungin; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000592:standards; D010456:Peptides, Cyclic / Q000494:pharmacology*
D000935:Antifungal Agents; D003470:Culture Media; D054714:Echinocandins; D055666:Lipopeptides; D008074:Lipoproteins; D010456:Peptides, Cyclic; D000077551:Micafungin