生物膜及相關感染性疾病

Biofilms: Clinical Implications and Applications

隨著醫學的進步，越來越多的管路及人工植入物被使用於醫療及改善人類的生活，當獲得這些醫療輔助的益處時，一個不能避免且麻煩的問題便是感染。一但這些醫材被細菌所感染，在這些無機物質的表面細菌會形成生物膜，而伴隨而來的是困難的治療以及高併發症或嚴重的後遺症。甚者必須將管路或人工植入物移除，使原本的醫療前功盡棄。而另外一些臨床困難治療的感染症，如：感染性心內膜炎、慢性骨髓炎、慢性攝護腺炎、甚至肺結核…等，近年來也發現生物膜的形成也在致病機轉及治療難度扮演著重要的角色。生物膜是近十年來對細菌感染研究的一個新的觀念，我們的敵人不是一隻一隻的細菌，而是一整群細菌社群，在群體中每個細菌的個體會有基因的交換傳遞，會有整體基因的調控，甚是會有分工合作的情形來對抗外在加予的生存壓力。雖然每一個細胞的個體都是單細胞生物，然而以社群方式的感染卻有著類似多細胞生物的協同合作。本文從生物膜生成的機轉到臨床相關疾病，到最後治療的應用作一說明。希望未來針對這樣的感染機轉能有更進一步的了解與研究，以其克服臨床上生物膜所帶來的困難。

The concept of biofilms, which was proposed over the past decades, provides a novel approach to understand the default state of bacteria in nature and even in certain types of human infection. A biofilm is a bacterial community that shows gene expression different from that of planktonic bacteria; bacteria show these expression differences to adapt or respond to environmental stress. The mechanism of biofilm development includes 4 steps: attachment, accumulation, architecture formation, and dispersal. Once the biofilm is formed, the bacterial community integrates and coordinates its gene expression through quorum sensing. As stated by the US CDC, more than 60% of the clinically infectious diseases are associated with biofilm formation; biofilm formation is especially prominent in deep-site infections such as infective endocarditis, chronic osteomyelitis, chronic prostatitis, infections caused by stones in the urinary tract, and even pulmonary tuberculosis, catheter-related bloodstream infections, endotracheal tube-related nosocominal pneumonia, and many implant-related infections. Biofilm-associated infectious diseases often require a longer treatment course, have higher failure rates, and show poorer outcome because of increased medicine consumption. Some novel strategies were investigated to manage biofilm-associated infectious diseases. Some newly developed antibiotics or combinations of antimicrobial agents showed better effects on biofilm eradication. Small peptides that interfere with the quorum-sensing system were effective in disturbing gene adjustments in biofilms and eliminating the complications in animal models. Surface coatings of materials applied on catheters or medical implants were studied to reduce the attachment of bacteria, the first step of biofilm formation. Low-frequency, low-power ultrasonography is helpful in improving diagnosis and in the treatment of biofilm-associated diseases, and bioelectricidal effect was also seen in a chronic osteomyelitis rabbit model[Author5]. Further investigations on the applications of biofilms are needed to improve human health and facilitate infection control.