In vitro activity of five antifungal agents against clinical isolates of Saccharomyces cerevisiae.
We evaluated the in vitro activity of fluconazole, itraconazole, ketoconazole, 5-fluorocytosine and amphotericin B against 30 clinical isolates of Saccharomyces cerevisiae by a broth microdilution method, following the NCCLS recommendation. Testing was performed either in RPMI-1640 or yeast nitrogen base (YNB). YNB supported the growth of all isolates tested, while results in RPMI-1640 were not obtained for six isolates (20%). The MIC of all three azoles in YNB were one or two dilutions higher than those obtained in RPMI-1640 (P=0.0001 for fluconazole and itraconazole, P=0.03 for ketoconazole). Elevated MICs were observed for all three azoles, while all the isolates were susceptible to 5-fluorocytosine and amphotericin B. All MIC values were confirmed by spectrophotometric reading. Six strains of S. cerevisiae isolated from the faeces and consecutive blood cultures from an AIDS patient over a 7-month period were typed by electrophoretic karyotyping (EK). EK showed the maintenance of the same karyotype over time suggesting that the faecal isolate changed from a colonizing to infection-causing strain. The relative resistance of S. cerevisiae to azole drugs as well as its ability to cause widespread infections may promote the emergence of this species as a pathogen in immunosuppressed patients.
Barchiesi
F
F
Institute of Infectious Diseases and Public Health of the University of Ancona, Italy. cmalinf@popcsi.unian.it
Arzeni
D
D
Compagnucci
P
P
Di Francesco
L F
LF
Giacometti
A
A
Scalise
G
G
D017088:AIDS-Related Opportunistic Infections / Q000382:microbiology*; D000666:Amphotericin B / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology*; D001393:Azoles / Q000494:pharmacology; D001769:Blood / Q000382:microbiology; D004587:Electrophoresis, Agar Gel; D005243:Feces / Q000382:microbiology; D006801:Humans; D007621:Karyotyping; D008826:Microbial Sensitivity Tests; D009181:Mycoses / Q000382:microbiology*; D012441:Saccharomyces cerevisiae / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification
D000935:Antifungal Agents; D001393:Azoles; D000666:Amphotericin B