Effectiveness of Different Disinfectants Used in ICUs on Candida Biofilms at Different Concentrations and Contact Times

Document Type : New and original researches in the field of Microbiology.

Authors

1 Medical Microbiology and Immunology Department, Faculty of Medicine, Beni-Suef University, Egypt

2 Critical Care Medicine Department, Faculty of Medicine, Beni-Suef University, Egypt

Abstract

Background: Candida species cause a wide spectrum of diseases, including hospital-acquired and device-associated infections. The biofilm formation is a major virulence factor in Candida pathogenesis and the cells in biofilm show enhanced resistance to disinfectants. Objectives: The aim of this study was to evaluate the efficiency of the commonly used hospital disinfectants [ethanol, chlorine (sodium hypochlorite; SH) and peracetic acid (PA)] on biofilms induced by clinical Candida isolates. Methodology: Isolation and identification of Candida spp. were conducted by the various conventional methods, in the Microbiology laboratory, Faculty of Medicine, Beni-Suef University. Biofilms were grown in 96 well flat-bottomed microtiter plates and they were evaluated by crystal violet (CV) assay method. Thereafter, the selected disinfectants concentrations were adjusted to manufacturer’s recommendations for instrument disinfection: 70% ethanol, 5.25% SH (5000 ppm of chlorine) and 0.2% PA. They were also prepared at the 1/2 and 1/4 of their recommended concentrations to evaluate the activity of lower concentrations. The biofilms were then treated with the disinfectants at contact times of 1, 5 and 10 minutes. Results: Positive samples for Candida were distributed as follows; urine samples 23 (76.7%), sputum samples 5 (16.7%), a blood sample 1(3.3%) and a pus sample 1 (3.3%). C.albicans were detected in 23 (76.7%) of yeast yields isolated, while, 7 (23.3%) were C.non albicans. Strong biofilm formation was noticed in 9 (30%) isolates, moderate in 9 (30%), while 12 out of 30 (40%) showed weak biofilm formation. Degree of biofilm reduction using the three disinfecting agents was assessed with different concentrations and different contact times. The findings showed that increasing the concentration of the used disinfectants (1/2, 1/1) together with exposure for longer contact times (5,10 min) were leading to more increase in the percentage of reduction of biofilm formation that was evidently higher in C.albicans than that of C.non albicans.

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