以白色念珠菌為模式探討甲殼素增強光動力殺菌的效果

Chitosan augments photodynamic inactivation against Candida albicans

張博涵(Po-Han Chang)

指導教授 ： 陳進庭

國立臺灣大學/生命科學院/微生物與生化學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.00870

摘要

由於醫學的發展產生了各式各樣的醫療器材和藥物，使得以往無法治癒的疾病，得以治療。抗菌藥物的使用，雖然挽回不少病人之生命，但也使伺機性病原菌造成的感染病症大量地增加，進而引發院內感染。近年來真菌感染已成為院內感染的主要病因之一，並且由於真菌和人類一樣屬真核生物，因此抗真菌藥物一直有副作用太強的問題。此外，由於感染個案的增加，抗真菌藥物被頻繁使用，因而引發抗藥性的問題。光動力殺菌（Photodynamic inactivation）為一別於傳統抗菌藥物治療微生物感染的方法；光動力殺菌過程中光感物質可迅速地累積在菌體表面，並經由特定波長的光源激發後，產生單態氧及自由基對微生物細胞進行毒殺，形成不可逆的傷害。本實驗室先前研究發現，甲殼素（chitosan）應用在抗生素治療中，能降低抗生素的使用濃度，應用在光動力作用上，能夠提升光動力作用抑制細菌生長的效果。
在本研究中我們發現，甲殼素能夠增強光動力作用抑制白色念珠菌（Candida albicans）的生長。我們將甲殼素與白色念珠菌進行培養時，發現白色念珠菌的存活率並未受到顯著抑制，但經過光動力作用，對菌體造成一定程度傷害後，短時間內菌體存活率即明顯受到甲殼素的抑制。進一步研究探討發現，減少光感物質使用濃度，並增加甲殼素培養時間與濃度，都能有效抑制白色念珠菌存活率，顯示甲殼素應用於光動力殺菌上的潛力。雖然白色念珠菌抗藥性菌株與生物膜對光動力作用的抗性都明顯高於野生型菌株，但經過光動力作用後，加入甲殼素培養，抗藥性菌株與生物膜存活率皆明顯受到抑制。本研究亦發現，以帶正電微脂體包埋光感物質能有效提升光動力殺菌的效果。

關鍵字

光動力殺菌 ； 生物膜 ； 抗藥性菌株 ； 甲殼素

並列摘要

Candida albicans is an opportunistic pathogen in human normal flora. Candida albicans are able to produce both superficial and systemic infections, in immunocompromised hosts. The overall incidence of candidemia has increased persistently worldwide during the second half of the 20th century. In recent years, fungal infections has become one of the leading cause of nosocomial infection. Moreover, drug-resistance is a growing problem largely due to the widespread use of antifungal agents in medicine. Therefore, it is necessary to develop alternative antimicrobial methods which are effective in the treatment of multi-drug resistant fungal infections.
In this study, we found chitosan can augment the photodynamic inactivation (PDI) mediated by TBO and Ce6 against Candida albicans with a 30-min incubation after PDI. At conditions where the PDI could kill the microbe for about 2 to 4-log scale, the addition of chitosan at as low as 0.25% for 30 minutes after the PDI could further eradicate the Candida albicans (originally was 107 CFU/ml). However, without PDI treatment, chitosan alone did not exert significant antimicrobial activity for the for 30-minute incubation. Similar results were also found in drug-resistant strains and the biofilm of Candida albicans. These results indicate that the synergistic effect of chitosan worked after the fungal damage induced by PDI.

並列關鍵字

Photodynamic inactivation ； Biofilm ； Chitosan

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