Biofilm Formation by Candida tropicalis and Efficacy of Liposomal Amphotericin B for Prevention of Biofilm Development

Y. Yamagishi, A. Kawai, H. Mikamo

Author address: 

Aichi Med. Univ., Aichi, Japan

Abstract: 

Background: There are an increasing number of cases of infection with non-albicans Candida. One of the major non-albicans fungi, Candida tropicalis, is likely to form biofilms, which cause a poor prognosis. This study was conducted to examine the process of biofilm formation by C. tropicalis and the antifungal activity of liposomal amphotericin B (LAB) against biofilmforming strains, using time-lapse imaging. Methods: C. tropicalis was inoculated on a silicone tube and media were incubated during perfusion to reproduce biofilm formation in a catheter in clinical practice, with shaking for 90 min to promote adherence of fungi. The silicone tube was incubated at 37°C with perfusion of 5% serum with Sabouraud glucose agar and imaged by timelapse photography. Biofilm formation was confirmed by observation of a fungi mass on the silicone tube and fluorescent staining with Fin-1 and concanavalin A.Results: After 14 h, C. tropicalis grew with gas generation, probably because of the high rate of biofilm formation and metabolic activity. After 17 h, the whole tube was covered with thick biofilms of C. tropicalis. LAB caused marked degeneration of C. tropicalis before biofilm formation and inhibited expansion of mycelia, resulting in blocking of biofilm formation. At 6 h after addition of LAB, the antifungal activity of LAB had reduced the fungi level to below that of the untreated control.Conclusions: This is the first study to examine the in vitro activity of LAB against C. tropicalis biofilms. The results suggest that LAB may be effective for treatment of infections caused by catheter-related non-albicans biofilms. This finding requires confirmation in studies including a large number of C. tropicalis strains.
2016

abstract No: 

SUNDAY-422

Full conference title: 

ASM Microbe 2016
    • ASM microbe 1st (2016)