Zanetti Franca, De Luca Giovanna, Sacchetti Rossella
Department of Medicine and Public Health, University of Bologna, Via S. Giacomo, 12-40126 Bologna, Italy.
Int J Food Microbiol. 2009 Jan 15;128(3):446-52. doi: 10.1016/j.ijfoodmicro.2008.10.007. Epub 2008 Nov 1.
Three microfiltered water dispensers (MWDs) for domestic use were bacteriologically monitored over a period of 1 year to evaluate their hygienic status and to compare the ability of two disinfectants (peracetic acid and hydrogen peroxide) to ensure adequate bacteriological quality of the dispensed water. To this end, two dispensers were purposely contaminated with a strain of Pseudomonas aeruginosa of environmental origin. A total of 324 samples of input and output water were analyzed. Heterotrophic plate count (HPC) bacteria at 22 degrees C and 36 degrees C, total coliforms (CT), Escherichia coli (EC), enterococci (ENT), P. aeruginosa and Staphylococcus aureus were enumerated. Throughout the study period, the supply water was always of excellent bacteriological quality. All water samples taken from the MWDs complied with the legal requirements for drinking water: CT, EC, ENT and S. aureus were all consistently absent. P. aeruginosa was never isolated from the uncontaminated dispenser. However, an increase in HPCs up to levels of 10(3)-10(4) cfu/mL was found in the dispensed water. Under the present operative conditions, hydrogen peroxide was seen to be more effective than peracetic acid in controlling bacterial contamination in the water circuits. Periodic disinfection with hydrogen peroxide made it possible to obtain water with HPC levels conforming to Italian regulations for drinking water (< or =100 cfu/mL) as well as to the levels recommended by the American Dental Association (ADA) (< or =200 cfu/mL). Furthermore, in the contaminated circuits, H(2)O(2) disinfection led to a reduction in the concentrations of P. aeruginosa to only a few colony forming units/100 mL or to a complete, albeit temporary, disappearance of the microorganism. In conclusion, hydrogen peroxide at 3% can be proposed as a suitable product for periodic disinfection of domestic MWDs, taking into consideration also its low cost and easy availability.
对三台家用微滤饮水机（MWD）进行了为期1年的细菌学监测，以评估其卫生状况，并比较两种消毒剂（过氧乙酸和过氧化氢）确保所供应水的细菌学质量达标的能力。为此，故意用一株环境来源的铜绿假单胞菌污染了两台饮水机。共分析了324份进水和出水样本。对22℃和36℃下的异养平板计数（HPC）细菌、总大肠菌群（CT）、大肠杆菌（EC）、肠球菌（ENT）、铜绿假单胞菌和金黄色葡萄球菌进行了计数。在整个研究期间，供水的细菌学质量始终优良。从MWD采集的所有水样均符合饮用水的法定要求：CT、EC、ENT和金黄色葡萄球菌始终均未检出。未受污染的饮水机中从未分离出铜绿假单胞菌。然而，在所供应的水中发现HPC增加至10³-10⁴ cfu/mL的水平。在当前的操作条件下，过氧化氢在控制水路中的细菌污染方面比过氧乙酸更有效。用过氧化氢进行定期消毒能够使水中的HPC水平符合意大利饮用水法规（≤100 cfu/mL）以及美国牙科协会（ADA）推荐的水平（≤200 cfu/mL）。此外，在受污染的水路中，H₂O₂消毒使铜绿假单胞菌的浓度降低至仅几个菌落形成单位/100 mL，或者使该微生物完全（尽管是暂时的）消失。总之，考虑到3%的过氧化氢成本低且易于获取，可建议将其作为家用MWD定期消毒的合适产品。
