Biocide resistance of Candida and Escherichia coli biofilms is associated with higher antioxidative capacities

Summary Background Most clinical guidelines for the use of biocides have been developed for planktonic micro-organisms, but in nature, most micro-organisms live as surface-adherent communities or biofilms. Aim To evaluate the effectiveness of commonly used biocides against Escherichia coli and Candi...

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Bibliographic Details
Published in:The Journal of hospital infection 2012-06, Vol.81 (2), p.79-86
Main Authors: Leung, C.Y, Chan, Y.C, Samaranayake, L.P, Seneviratne, C.J
Format: Article
Language:English
Subjects:
Biocides
Biofilm
Biofilms - drug effects
Biological and medical sciences
Candida
Candida - drug effects
Candida - physiology
Candida - ultrastructure
Catalase - biosynthesis
Disinfectants - pharmacology
Drug Resistance, Bacterial
Drug Resistance, Fungal
Escherichia coli
Escherichia coli - drug effects
Escherichia coli - physiology
Escherichia coli - ultrastructure
Gene Expression Profiling
Humans
Infectious Disease
Infectious diseases
Medical sciences
Microbial Sensitivity Tests
Microbial Viability - drug effects
Microscopy, Confocal
Microscopy, Electron, Scanning
Oxidative Stress
Stress, Physiological
Superoxide Dismutase - biosynthesis
Superoxide Dismutase-1
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Summary:Summary Background Most clinical guidelines for the use of biocides have been developed for planktonic micro-organisms, but in nature, most micro-organisms live as surface-adherent communities or biofilms. Aim To evaluate the effectiveness of commonly used biocides against Escherichia coli and Candida spp. in three distinct growth phases: planktonic, adhesion and biofilm. Methods Ultrastructural, architectural and cellular viability changes following a 5 min exposure to biocide were monitored by scanning electron microscopy and confocal laser scanning microscopy using fluorescent dyes. Comparative transcript expression of the antioxidants SOD1 and CAT1 in the planktonic and biofilm phases was evaluated using quantitative real-time polymerase chain reaction. Findings E. coli and Candida spp. in the planktonic phase were susceptible to all the tested biocides at the recommended concentrations. However, early adhesion and late biofilm phases of both were less susceptible to the biocides, and exceeded the recommended concentrations on several occasions. A short period of biocide exposure failed to fully eradicate the adherent microbial cells, and they recovered from the biocide challenge, forming biofilm on the biocide-treated surfaces. The biofilm phase showed higher expression of SOD1 and CAT1. Conclusion The recommended concentrations of biocides for clinical disinfection in the hospital setting may not fully eradicate the adhesion or biofilm phases of E. coli and Candida spp. Higher antioxidative capacities in microbial biofilms may be responsible for the resistance of biofilms against clinical biocides.
ISSN:0195-6701
1532-2939
DOI:10.1016/j.jhin.2011.09.014