Candida tropicalis Biofilms: Biomass, Metabolic Activity and Secreted Aspartyl Proteinase Production

Abstract

According to epidemiological data, Candida tropicalis has been related to urinary tract infections and haematological malignancy. Several virulence factors seem to be responsible for C. tropicalis infections, for example: their ability to adhere and to form biofilms onto different indwelling medical devices; their capacity to adhere, invade and damage host human tissues due to enzymes production such as proteinases. The main aim of this work was to study the behaviour of C. tropicalis biofilms of different ages (24-120 h) formed in artificial urine (AU) and their ability to express aspartyl proteinase (SAPT) genes. The reference strain C. tropicalis ATCC 750 and two C. tropicalis isolates from urine were used. Biofilms were evaluated in terms of culturable cells by colony-forming units enumeration; total biofilm biomass was evaluated using the crystal violet staining method; metabolic activity was evaluated by XTT assay; and SAPT gene expression was determined by real-time PCR. All strains of C. tropicalis were able to form biofilms in AU, although with differences between strains. Candida tropicalis biofilms showed a decrease in terms of the number of culturable cells from 48 to 72 h. Generally, SAPT3 was highly expressed. C. tropicalis strains assayed were able to form biofilms in the presence of AU although in a strain- and time-dependent way, and SAPT genes are expressed during C. tropicalis biofilm formation.

Approaches by Rhodotorula mucilaginosa from a chronic kidney disease patient for elucidating the pathogenicity profile by this emergent species

“…However, in contrast to the extensive literature dealing with biofilms of Candida sp. [18,20,35], few studies on the biofilm produced by isolates of medical interest of R. mucilaginosa are available. This lack of knowledge deserves concern, since serious and fatal infections due this specie have been related to the formation of biofilms on medical devices [11, 12].…”

“…The present study is the first one aiming to characterize the biofilm production by R. mucilaginosa on different ages (24, 48 and 72 hours), then we employed the classic methods used in studies with Candida sp. biofilms [35, 48], that are CFU, CV, XTT and microscope, addressing to R. mucilaginosa . These results are presented on Fig 03 and Table 2, and complemented by the quantification of the extracellular matrix components determined on the same times (Table 02).…”

“…In addition, we saw a peak of metabolic activity in 24 hours, and soon afterwards a decrease of this activity, being that in 72 hours, these cells were probably “dormant” [35]. Metabolically “dormant” yeast cells are also known as persistent cells, which originate stochastically as phenotypic variants within biofilms [20].…”

“…The absorbance values 492 nm to XTT assay and 620 nm to CV assay were standardised per unit area of well (absorbance/cm 2 ). The absorbance values of the negative controls wells were subtracted from the values of the test wells to account for any background absorbance [35].…”

Protective Activity of Probiotic Bacteria Against Candida albicans: An In Vitro Study

“…5 HEp-2 Cell Adhesion Assay Adhesion assay was carried out in the Department of Microbiology, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran. Adhesion of C. albicans strain to HEp-2 cells was tested as described by Negri et al 13 To evaluate the effect of L. acidophilus on the adherence of C. albicans to HEp2 cells, 1.5 × 10 6 CFU/mL of yeast cells, 1.5 × 10 6 CFU/mL of probiotic bacteria, or both were added to each well of a 12-well plate with a coverslip at the bottom, covered with a dense layer of HEp-2 cells. After two hours of incubation at 37°C in 5% CO 2 , each well was rinsed to remove the non-attached microorganisms.…”