Impact of the Disk Diffusion Test on Fluconazole De-Escalation in Patients with Candidemia

Disk diffusion (DD) is a simple antifungal susceptibility method for Candida. This study examined the impact of fluconazole DD testing on antifungal de-escalation. We enrolled patients with candidemia whose Candida isolates were tested for fluconazole susceptibility using DD between January 2019 and January 2020. The historical controls were patients with candidemia who underwent fluconazole susceptibility testing using the broth microdilution (BMD) method. Clinical data including antifungal therapy were analyzed. In total, 108 patients were enrolled. Most baseline characteristics were comparable between the groups. C. tropicalis was the predominant isolate (54.6%), followed by C. albicans (17.6%). The rates of antifungal de-escalation within 72 h were 25.9 and 9.3% in the DD and BMD groups, respectively (p = 0.023). The median time to de-escalation was 3 days in the DD group, versus 6 days in the BMD group (p = 0.037). The 14-day mortality rate and antifungal cost tended to be lower in the DD group. There were no differences in the length of hospital stay and treatment-related complications between the two groups. The agreement between the DD and BMD results was 90%. DD testing can be substituted for BMD to enhance antifungal de-escalation and antifungal stewardship.