Cappelli Gianni, Sereni Luisa, Scialoja Maria Grazia, Morselli Massimo, Perrone Salvatore, Ciuffreda Angela, Bellesia Massimo, Inguaggiato Paola, Albertazzi Alberto, Tetta Ciro
Department of Nephrology, University Hospital of Modena, Italy.
Nephrol Dial Transplant. 2003 Oct;18(10):2105-11. doi: 10.1093/ndt/gfg344.
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.
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 degrees 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).
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.
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.
生物膜由附着在几乎任何表面的微生物群落组成。我们评估了在故意污染的血液透析监测仪的液压回路中形成的生物膜是否会改变不同消毒方式对细菌和内毒素浓度的消毒效果。
将水性铜绿假单胞菌（109）悬浮液循环1小时，并在监测仪的液压回路中静置72小时（稳定期）。然后通过不同的物理（加热，85摄氏度）或化学（次氯酸盐或过氧乙酸）消毒方式对监测仪进行清洗和消毒（方案A）。在方案B中，细菌悬浮液也循环1小时，但随后立即通过不同的化学消毒方式（次氯酸盐或过氧乙酸）对监测仪进行清洗和消毒。
在稳定期（方案A）后，通过扫描和共聚焦激光电子显微镜观察到生物膜形成，但在监测仪立即清洗和消毒时（方案B）未观察到生物膜形成。在存在生物膜的情况下（方案A），加热结合柠檬酸是降低菌落形成单位和内毒素浓度最有效的方式，而单独加热是最无效的消毒方法。用稀释的过氧乙酸处理（60小时）可完全防止生物膜形成。在不存在生物膜的情况下（方案B），化学消毒对菌落形成单位和内毒素浓度均有效。
我们发现生物膜的形成可能会显著降低目前可用消毒方式的效果。因此，应定期在血液透析监测仪中使用不同的消毒方式以及除垢（用柠檬酸）和消毒（物理/化学剂）的联合作用。此外，在监测仪不使用时应采用用稀释的过氧乙酸处理的方法。
