The Risk of Biofilm
生物膜的風險
Because of the high microbiological requirements on water for pharmaceutical use and the high risks linked to a microbiological water contamination, enormous efforts are taken in the pharmaceutical industry to prevent from bacterial growth in water systems. Such systems are normally composed of the water treatment as well as the storage and distribution system.
由于制藥用水里較高的微生物要求，以及與水中微生物污染相關的高風險，制藥行業已投入巨大精力防止水系統中的微生物滋生。這樣的系統通常由水處理系統和存貯分配系統組成。
The dangers arising from biofilms are hereby often underestimated.
而通常來自生物膜的危險則會被低估。
Sanitisation measures are often directed to (aquatic) bacteria. Those bacteria reach the high-purity - and thus nutrient-poor - waters of the pharmaceutical industry, but only to an insignificant extent. For energy reasons, a small concentration of nutrients coming from the feed water can form deposits on the inner surfaces of piping system for example. Those surfaces are also a promising location for bacteria to settle and proliferate. An additional favourable factor for that settlement and proliferation of bacteria is the low flow rate on the surfaces of the pipes, which even tends to be inexistent in laminar flows. Therefore, without any mechanical action, a flow washing of the bacteria can't be expected. Bacteria in formatting biofilms behave differently than in a free state. This leads to the formation of layers containing polysaccharide which overlie the bacteria of the biofilm as a protector.
滅菌措施通常是針對（水性）細菌的。這些細菌進入到高純度---因而也是沒有營養的制藥用水中，但僅僅只是微量。由于能力的緣故，來自源水中的低濃度營養物可能會在管道系統的內表面沉積。這些表面也會有地方給細菌安身并迅速繁殖。細菌安身和滋長另一個有利因素是管道表面的水流速較低，甚至在平流中都不存在水流。因此，沒有任何機械措施的情況下，不能指望用水流來沖刷細菌。正在形成生物膜的細菌行為方式與自由態時是不同的，它會導致形成多層含有多聚糖的膜，覆蓋在生物膜的表面成為保護層。
Within this protection layer, the bacteria are characterised by a very much higher tolerance to heat, disinfectants and dehydration than in a free (aquatic) state. This is a reason why bacteria in biofilms can survive sanitisation measures. Even if all cells within a film are killed, the cell-polysaccharide-compound remaining on the surface offers an ideal breeding ground for other bacteria which may come isolated from the feed water into the water system. This means that both living and dead biofilms present a risk for the pharmaceutical finished product. On the one hand, living bacteria or parts of the biofilm compound keep on detaching again and again and thus present a microbiological source of contamination for other parts of the system. On the other hand, killed-off biofilm fragments constitute a source of contamination with endotoxins.
在此保護層中，細菌特性比起自由態（水性）來變成能非常能耐熱、耐消毒劑和脫水反應。這就是為什么生物膜中的細菌可以在滅菌后仍存在的原因。甚至即使膜中所有細菌全部被殺死，細菌多聚糖化合物仍保留在表面，為其它細菌提供理想的營養地，這些細菌可能來自進入水系統的源水。這意味著活的和死的生物膜都顯示出對藥品的風險。一方面，活菌或生物膜化合物的一部分保持反復依附，因而成為系統中其它部分污染的微生物來源。另一方面，被殺滅的生物膜碎片形成內毒素污染源。
That's why the fight against biofilms is and remains a challenge for the pharmaceutical industry. It is essential to set appropriate measures for the water system (biofilm management) and to implement them consistently - for example hot storage, sanitisation with steam or ozone. Therefore, as early as the planning phase it is necessary to establish an appropriate design of the system counteracting the formation of biofilms - e.g. preventing from dead-legs or low points that cannot be emptied. Yet, the system operating is as essential as the design. Downtimes always present a higher risk of microbial growth. An uncontrolled weekend is already sufficient to lead to a significant bacterial contamination. "Keep the system running" is thus the best protection of a well-designed water system.
這就是為什么與生物膜做斗爭對于制藥行業來說一直是一個挑戰。為水系統制訂恰當的措施（生物膜管理），以及維持一致實施這些措施是非常重要的—例如，熱存貯、蒸汽或臭氧滅菌。因此，提前到規劃階段來說，都有必要制訂適當的系統設計，應對生物膜生成---例如，防止死管或可能無法排空的低點。還有，系統盡可能按設計方案運行。停機總會帶來更高的微生物生長風險。一個不受控的周末就足以導致嚴重的細菌污染。“保持系統運行”因而成為對設計良好的水系統的最好保護。
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