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Canadian Journal of Infectious Diseases
Volume 10 (1999), Issue 1, Pages 27-32
Original Article

No Increase in Frequency of Antifungal Resistance among Yeasts Isolated from Normally Sterile Sites in Patients at Foothills Hospital from 1993 to 1996

A Patrick Gibb, Cheryl Thorson, and Harry van den Elzen

Departments of Microbiology and Infectious Diseases, University of Calgary, Foothills Hospital, Calgary, Alberta, Canada

Received 16 February 1998; Accepted 11 May 1998

Copyright © 1999 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


OBJECTIVE: To determine the prevalence of resistance to antifungal drugs among yeasts isolated from sterile sites from patients in one hospital and the relationship of resistance to antifungal use, and to assess whether resistance was increasing.

METHOD: Susceptibility testing performed by National Committee for Clinical Laboratory Standards (NCCLS) (Villanova, Pennsylvania) microdilution method and by E test. Antifungal use was determined by selected chart review and from pharmacy data.

SPECIMENS AND SETTING: Tertiary care adult hospital with neonatal intensive care.

POPULATION STUDIED: Distinct yeast isolates from sterile site specimens collected during the years 1993 to 1996.

RESULTS: A total of 132 yeast isolates were studied, of which 78 (59%) were Candida albicans. The proportion of C albicans remained steady over the four-year period, and there was no trend to increased resistance among C albicans. The number of isolates of all species with fluconazole microdilution minimum inhibitory concentration (MIC) greater than 8 mg/L in each of the four years were one of 32 in 1996, three of 26 in 1994, six of 33 in 1995, and one of 41 in 1996. A single isolate had an itraconazole microdilution MIC greater than 0.5 mg/L in each year. Prior use of antifungal therapy was rare in this patient population.

CONCLUSIONS: The increase in resistance to antifungal drugs reported by some centres did not occur in this institution over the course of the study. This experience may reflect differences in infection control practices and in patterns of use of antifungal agents. The NCCLS method was found to be superior to the E test as a routine method for testing susceptibility of yeasts.