Lehtola Markku J, Torvinen Eila, Kusnetsov Jaana, Pitkänen Tarja, Maunula Leena, von Bonsdorff Carl-Henrik, Martikainen Pertti J, Wilks Sandra A, Keevil C William, Miettinen Ilkka T
Environmental Microbiology Laboratory, National Public Health Institute, Department of Environmental Health, P.O. Box 95, FI-70701 Kuopio, Finland.
Appl Environ Microbiol. 2007 May;73(9):2854-9. doi: 10.1128/AEM.02916-06. Epub 2007 Mar 2.
Most of the bacteria in drinking water distribution systems are associated with biofilms. In biofilms, their nutrient supply is better than in water, and biofilms can provide shelter against disinfection. We used a Propella biofilm reactor for studying the survival of Mycobacterium avium, Legionella pneumophila, Escherichia coli, and canine calicivirus (CaCV) (as a surrogate for human norovirus) in drinking water biofilms grown under high-shear turbulent-flow conditions. The numbers of M. avium and L. pneumophila were analyzed with both culture methods and with peptide nucleic acid fluorescence in situ hybridization (FISH) methods. Even though the numbers of pathogens in biofilms decreased during the experiments, M. avium and L. pneumophila survived in biofilms for more than 2 to 4 weeks in culturable forms. CaCV was detectable with a reverse transcription-PCR method in biofilms for more than 3 weeks. E. coli was detectable by culture for only 4 days in biofilms and 8 days in water, suggesting that it is a poor indicator of the presence of certain waterborne pathogens. With L. pneumophila and M. avium, culture methods underestimated the numbers of bacteria present compared to the FISH results. This study clearly proved that pathogenic bacteria entering water distribution systems can survive in biofilms for at least several weeks, even under conditions of high-shear turbulent flow, and may be a risk to water consumers. Also, considering the low number of virus particles needed to result in an infection, their extended survival in biofilms must be taken into account as a risk for the consumer.
饮用水分配系统中的大多数细菌都与生物膜有关。在生物膜中，它们的营养供应比在水中更好，并且生物膜可以提供抵御消毒的庇护所。我们使用了一种螺旋桨式生物膜反应器，来研究鸟分枝杆菌、嗜肺军团菌、大肠杆菌和犬杯状病毒（CaCV，作为人类诺如病毒的替代物）在高剪切湍流条件下生长的饮用水生物膜中的存活情况。采用培养方法和肽核酸荧光原位杂交（FISH）方法分析了鸟分枝杆菌和嗜肺军团菌的数量。尽管在实验过程中生物膜中病原体的数量有所减少，但鸟分枝杆菌和嗜肺军团菌以可培养的形式在生物膜中存活了超过2至4周。通过逆转录 - PCR方法在生物膜中检测到CaCV超过3周。大肠杆菌通过培养在生物膜中仅可检测4天，在水中可检测8天，这表明它不是某些水源性病原体存在的良好指示物。对于嗜肺军团菌和鸟分枝杆菌，与FISH结果相比，培养方法低估了存在的细菌数量。这项研究清楚地证明，进入水分配系统的病原菌即使在高剪切湍流条件下也能在生物膜中存活至少几周，这可能对用水者构成风险。此外，考虑到导致感染所需的病毒颗粒数量很少，它们在生物膜中的长期存活必须被视为对消费者的一种风险。
