[Identification and antifungal susceptibility of Candida spp isolated from invasive mycoses. Influence of growth inhibition percentage to determine minimal inhibitory concentration].
BACKGROUND
An increase in the frequency of resistant strains to antifungal drugs has been detected in the last decade.


OBJECTIVE
To report the minimal inhibitory concentration (MIC) to amphotericin B, fluconazole, ketoconazole and itraconazole. To compare the MIC obtained with 80% and 50% of growth inhibition to the azoles.


METHODS
Fifty yeast strains isolated between 1998 and 1999, from 17 adults and 33 children with invasive mycosis were studied. Susceptibility was determined by broth microdilution method with RPMI 1640 plus glucose 2% according to the National Committee for Clinical Laboratory Standards (1997).


RESULTS
The most frequently isolated strains were C albicans in 27 cases and C parapsilosis in 12. All isolates were susceptible to amphotericin B. According to the MICs obtained with 80% of inhibition, 12 strains had MICs considered as resistant to azoles. Five strains were resistant both to fluconazole and itraconazole. Considering MICs obtained with 50% of inhibition, only five strains were found resistant to azoles (p < 0.05). Using this criterion, only one C glabrata strain was found to be simultaneously resistant to fluconazole and itraconazole.


CONCLUSIONS
Similar results in the pattern of susceptibility of Candida spp to azoles, to those reported abroad, are obtained when the MIC is calculated using 50% inhibition.
Alvarado
Daniel
D
Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
Díaz
María C
MC
Silva
Víctor
V
D000328:Adult; D000666:Amphotericin B / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology*; D002175:Candida / Q000187:drug effects* / Q000254:growth & development; D002177:Candidiasis / Q000382:microbiology; D002648:Child; D015725:Fluconazole / Q000494:pharmacology; D006131:Growth Inhibitors / Q000494:pharmacology; D006801:Humans; D017964:Itraconazole / Q000494:pharmacology; D007654:Ketoconazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests
D000935:Antifungal Agents; D006131:Growth Inhibitors; D017964:Itraconazole; D000666:Amphotericin B; D015725:Fluconazole; D007654:Ketoconazole