Impact of Fluconazole Disk Diffusion Susceptibility Testing on Antifungal Use in a University Teaching Hospital

JAMES S. LEWIS, PharmD1, YOLANDA M. LAUREL, RPh, MBA1, JAN E. PATTERSON, MD2, JAMES H. JORGENSEN, PhD3;

Author address: 

University Health System, San Antonio, TX, 2University of Texas Health Science Center, San Antonio, TX, 3University of Texas Health Sciences Center, San Antonio, TX.

Abstract: 

Background: Fluconazole disk diffusion susceptibility testing (FDDST) using NCCLS M44-P methodology was put into regular use in 6/2003. Prior to this, results of fluconazole (FCZ) susceptibility testing for Candida spp. required up to 7 days. FDDST provides results within 24h of Candida spp. isolation on blood agar. The test is inexpensive and easy to perform in a clinical microbiology laboratory. Recently, we noted increasing use of costly agents for Candida glabrata due to concerns over FCZ resistance. We evaluated whether the rapid availability of FDDST results would avoid unnecessary antifungal expenditures. Methods: Data on Candida spp. blood cultures and C. glabrata urine cultures from 1/2003 to 4/2004 were retrieved. Patients charts were reviewed for all above isolates with FDDST results. Data collected included patient location, species identified, FDDST results, antifungal(s) used, duration of therapy, and outcome. The antimicrobial management service (AMS) database was also checked for interventions on caspofungin, liposomal amphotericin B, and voriconazole related to FDDST. Results: A total of 65 individuals were identified with Candida spp. that had FDDST performed on them. 37 patients had FDDST results reported on Candida spp. blood isolates. 21 patients had FDDST results reported on C. glabrata urine isolates. The AMS database identified 2 C. glabrata isolates from respiratory samples and 5 other Candida spp. isolates from non-blood sites where FDDST contributed to changes in patients’ therapy. 4 C. glabrata isolates resistant to fluconazole were identified and all cases resulted in caspofungin use. The remaining 61 isolates tested were susceptible to FCZ (Resistance = 6%) Cost avoidance = (agent 1 8722; agent 2) x duration of therapy. All changes were from caspofungin to FCZ. 3 patients with blood isolates had their therapy changed with an estimated cost avoidance of $8,700. A total of 15 patients had their therapy altered based on FDDST results for a total cost avoidance of $38,600 in the 11 months that the test was being routinely used. Conclusion: FDDST has a positive impact on antifungal expenditures.
2004

abstract No: 

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Full conference title: 

42nd Annual Meeting Infectious Diseases Society of America
    • Infectious Diseases Society of America 42nd