ABSTRACT
BACKGROUND: Invasive infections due to Trichosporon spp. have increased recently and are frequently associated with indwelling medical
devices. Such infections which are associated with biofilm formation do not respond
to the routinely used antifungal agents and are often persistent, associated with
high mortality rate. Various methods have been described by researchers to evaluate
and quantify the biofilm formation.
AIM: This study was conducted to compare two methods of biofilm production by Trichosporon sp, i.e., test tube method with crystal violet (CV) staining and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl
tetrazolium bromide (MTT) assay.
MATERIALS AND METHODS: Seventy-two clinical isolates of Trichosporon spp. collected from various sources were considered for the study. The identity of
all the isolates was genotypically confirmed by Trichosporon-specific polymerase chain reaction (PCR). The isolates were further speciated phenotypically
using biochemical profile and growth characteristics which identified the isolates
as Trichosporon asahii (64/72), Trichosporon asteroides (5/72), Trichosporon cutaneum (2/72), and Trichosporon mucoides (1/72). Biofilm production was then evaluated and compared by test tube-CV method
and MTT assay.
RESULTS: All the Trichosporon isolates produced biofilm by MTT assay, whereas only 42 (53.6%) of the isolates were
detected to be biofilm producers by CV method. Furthermore, MTT assay could differentiate
better between weak and moderate biofilm producers as compared to CV method.
CONCLUSION: Hence, MTT assay is a reliable method for quantification of biofilm produced by Trichosporon spp. using 96-well microtiter plate.
Keywords
3-(4 - 5-dimethylthiazol-2-yl)-2 - 5-diphenyl tetrazolium bromide assay - biofilm
- crystal violet method -
Trichosporon sp