Effects of biofilm formation on haemodialysis monitor disinfection

• Published in: Nephrology, dialysis, transplantation dialysis, transplantation, 2003-10, Vol.18 (10), p.2105-2111
• Main Authors: Cappelli, Gianni, Sereni, Luisa, Scialoja, Maria Grazia, Morselli, Massimo, Perrone, Salvatore, Ciuffreda, Angela, Bellesia, Massimo, Inguaggiato, Paola, Albertazzi, Alberto, Tetta, Ciro
• Format: Article
• Language: English
• Subjects: Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Bacterial Infections - etiology; Bacterial Infections - prevention & control; biofilm; Biofilms; Biological and medical sciences; Colony Count, Microbial; contamination; cytokine; disinfection; Disinfection - methods; Emergency and intensive care: renal failure. Dialysis management; Equipment Contamination; Humans; Intensive care medicine; Medical sciences; microinflammation; Microscopy, Electron; monitor; Probability; Pseudomonas aeruginosa; Renal Dialysis - adverse effects; Renal Dialysis - instrumentation; Risk Assessment; Sensitivity and Specificity
• ISSN: 0931-0509; 1460-2385; 1460-2385
• DOI: 10.1093/ndt/gfg344

Background. Biofilms are composed of communities of micro-organisms adhering to essentially any surface. We evaluated whether biofilm formation in the hydraulic circuit of a purposely contaminated haemodialysis monitor would modify the efficacy of different disinfection modalities against bacteria and endotoxin concentrations. Methods. A water-borne Pseudomonas aeruginosa (109) suspension was recirculated for 1 h and was left standing for 72 h (stationary phase) in the hydraulic circuit of the monitor. The monitor was then washed and disinfected by different physical (heat, 85°C) or chemical (hypochlorite or peracetic acid) disinfection modalities (protocol A). In protocol B, the bacterial suspension was also recirculated for 1 h, but the monitor was then immediately washed and disinfected by different chemical disinfection modalities (hypochlorite or peracetic acid). Results. Biofilm formation was revealed by scanning and confocal laser electron microscopy after the stationary phase (protocol A), but was absent when the monitor was immediately washed and disinfected (protocol B). In the presence of biofilm (protocol A), heat in association with citric acid was the most effective modality for reducing both colony forming units and endotoxin concentrations, whereas heat by itself was the least effective method of disinfection. Dwelling (60 h) with diluted peracetic acid completely prevented the formation of biofilm. In the absence of biofilm (protocol B), chemical disinfection proved to be effective against both colony forming units and endotoxin concentrations. Conclusions. We found that biofilm formation may markedly reduce the efficacy of presently available disinfection modalities. Therefore, different disinfection modalities and the combined action of descaling (by citric acid) and disinfection (physical/chemical agents) should be used periodically in haemodialysis monitors. In addition, dwelling with diluted peracetic acid should be adopted whenever monitors are not in use.