Impact of flow conditions and surface type on the resistance of Candida tropicalis biofilms to desinfection

STEWART, PHILLIP; TARIFA, MARÍA CLARA; PITTS, BETSEY

Valencia

Congreso; 7th Congress of European Microbiologists FEMS 2017; 2017

BACKGROUNDWhile biofilm formation is a general characteristic of microbes, features such as architecture, matrix composition, and resistance to antimicrobials are species and substrate dependent.OBJECTIVESThe aim was to delve into the response in thickness, architecture, and mechanical resistance of Candida tropicalis biofilms.METHODSThe strain used was Candida tropicalis ATCC 13803, which was cultivated in SDB for 48 and 72 h on stainless steel (SS) and polycarbonate coupons (4.05 cm2). Two flow conditions were tested: turbulent flow with a CDC reactor (Biosurface Technologies, USA) (flow rate of 4 ml/min, speed of 200 rpm); and for static flow 12 wells plates were used. Coupons were subjected to the analysis of: mechanical resistance in a flow cell, counting, CLSM imaging and cryosectioning. For disinfection, coupons were treated with solutions of 200 ppm of NaClO for 15 minutes, and then neutralized in sodium thiosulfate 0.2%.CONCLUSIONSBiofilms were observed on SS and polycarbonate at 48 and 72 h after cell staining with LIVE/DEAD® Kit, increasing with Re and time. Flow conditions impacted biofilm architecture and thickness, under turbulent flow biofilms presented mushroom shapes with hyphae and the largest increase in thickness (> 90 μm), whereas static flow presented homogeneous layers of rounded cells (up to 30 μm).The results underline that the biofilm resistance to NaClO depended on the growth time, the surface type and the type of flow. At 48 h log reductions ranged between 0.2-0.58 and 1.2-1.36 for turbulent and static flow, respectively whereas at 72 h were of 0.32-1.7 and 2.65-2.82.