In vitro activity of fluconazole and amphotericin B against Candida inconspicua clinical isolates as determined by the time-kill method.
Candida inconspicua is an emerging pathogen in immunocompromised patients possessing inherently decreased susceptibility to fluconazole. We determined the MICs and killing activity of fluconazole and amphotericin B against C. inconspicua clinical isolates as well as reference strain C. inconspicua ATCC 16783 for comparison. MICs were determined using the standard broth microdilution method. Killing rates were determined using time-kill methodology at 0.5-16 x MIC fluconazole and amphotericin B concentrations. Fluconazole and amphotericin B MIC values varied between 16-128 mg/l and 0.5-1 mg/l, respectively. In time kill-assays fluconazole showed fungistatic effect at 1-16 x MIC concentrations against all tested strains after 24 h-incubation, but became fungicidal after 48 h at 4-16 x MIC concentrations. The time necessary to achieve fungicidal endpoint at 1 mg/l amphotericin B concentration ranged from 2 to 24 h. Our in vitro results confirm the data that fluconazole is ineffective against C. inconspicua at the fluconazole serum concentration attainable in humans. Amphotericin B due to its rapid killing activity seems to be a good alternative for the treatment of infections caused by C. inconspicua.
Institute of Medical Microbiology, Doctoral School, Semmelweis University, Budapest, Hungary.
Zsuzsanna
Z
Szabó
Georgina
G
Sóczó
Cecilia
C
Miszti
P
P
Hermann
F
F
Rozgonyi
D000666:Amphotericin B / Q000494:pharmacology*; D002175:Candida / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D002177:Candidiasis / Q000382:microbiology*; D015725:Fluconazole / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability; D013997:Time Factors
D000666:Amphotericin B; D015725:Fluconazole