Susceptibility of yeast isolates from defined German patient groups to 5-fluorocytosine.
Susceptibility and development of resistance to 5-fluorocytosine (5-FC) in Candida strains isolated from defined German groups of probands was investigated. 5-FC susceptibility was determined in a microdilution assay in yeast nitrogen base after 24 h of incubation at 37 degrees C. The range of 5-FC concentration investigated was between 0.015 and 16 micrograms ml-1. Isolates with a minimum inhibitory concentration (MIC) of > 16 micrograms ml-1 were regarded as 5-FC resistant. In total 335 Candida isolates were investigated, and 20 of them (6.0%) were found to be resistant. The Candida isolates were rather different with respect to their origin: out of 57 vaginal isolates from non-risk patients from Southern Germany 3.5% were 5-FC-resistant strains. One hundred and fifty-nine isolates from the urine of long-term intensive care patients from the whole of Germany showed 5-FC resistance (6.3%). Out of 74 isolates of different localization from intensive care patients of the University Clinics of Freiburg, 10.8% showed 5-FC resistance. Among 45 isolates from the oral cavity of HIV-positive patients from the Frankfurt region, no 5-FC-resistant strain was found. The epidemiology of 5-FC resistance is based mainly on the percentage of non-albicans isolates of the proband groups (C. tropicalis, C. krusei and others), and is less based on the frequency of Candida albicans serotype B isolates. In sequential observations with individual intensive care patients, no increase of 5-FC resistance in their Candida isolates could be observed with longer periods of hospitalization.
Weber
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E Hoffmann-La Roche Ltd. Basel, Switzerland.
Polak
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A
D002175:Candida / Q000187:drug effects*; D004352:Drug Resistance, Microbial; D005260:Female; D005437:Flucytosine / Q000494:pharmacology*; D005858:Germany; D006801:Humans; D008826:Microbial Sensitivity Tests; D015203:Reproducibility of Results
D005437:Flucytosine