克雷伯氏肺炎桿菌 (Klebsiella pneumoniae；KP)是常見於人類纇道的細菌，在細胞壁外有厚莢膜，由單醣聚合而成，可避免被宿主免疫系統之吞噬及補體作用消滅，是主要的致病因子。在台灣，克雷伯氏肺炎桿菌容易在糖尿病患者引起肺炎、敗血症、肝膿瘍等等併發症，病患常因抗藥性的問題，導致治療不當造成高死亡率，因此對於臨床上的威脅甚大。本研究以搜尋有效的中藥來抑制克雷伯氏肺炎菌中莢膜多醣體的生合成為主，並探討添加不同的中藥後，觀察莢膜多醣體、血清毒殺能力與存活率之間的關係。
實驗設計為將克雷伯氏肺炎桿菌培養於添加中藥及不添加中藥的細菌培養液中，經過隔夜震盪培養，以離心沉澱法以及測量光學密度為初步篩選可抑制菌體中莢膜多糖體生合成之可能有效中藥，之後藉由定量莢膜多醣體及觀察其存活率，確定有效之中藥後，再進行血清毒殺實驗。
本研究共篩選了45 種中藥，其中添加黃柏及五倍子的培養液可以有效抑制克雷伯氏肺炎桿菌中莢膜多醣體的生合成，而且經由塗盤後確認菌數，也發現可有效抑制細菌的生長。此外，在血清毒殺實驗中，添加五倍子更可有效增加血清對克雷伯氏肺炎桿菌的毒殺能力，減少克雷伯氏肺炎桿菌的毒性。根據此研究結果顯示，五倍子除了可有效抑制細菌生長外，更可進一步減少克雷伯氏肺炎桿菌莢膜多醣體的生合成，以利於人體血清的有效攻擊，降低感染的機會，然而在臨床使用則需要更多的研究來進一步探討。
Klebsiella pneumoniae is common bacteria in the human Intestine. In K. pneumoniae, whit thick capsule polysaccharide is a major causative factor to be avoided by the host immune system to eliminate the role of phagocytosis and complement during the infection. In Taiwan, K. pneumoniae is the predominant pathogen responsible for pyogenic liver abscess in diabetic patients. The recent emergence and dissemination of antibiotic resistance have increased the treatment difficulties of K. pneumoniae infection. Therefore, development of an antimicrobial approach to block the virulence factor production has been evaluated.
In this study, we attempted to search the effective Chinese herbs to inhibit capsular polysaccharide biosynthesis in K. pneumoniae. By adding various Chinese herbs into the culture medium to observe the effects on capsular polysaccharides, serum resistance and bacteria survival rate in K. pneumoniae.
This study, in a total of 45 kinds of Chinese herbs screening, Cortex Phellodendri and Galla Chinensis can be effectively suppressed the capsular polysaccharide biosynthesis and bacterial growth in K. pneumoniae. In the serum bactericidal activity, Galla Chinensis can effectively decrease the serum resistance in K. pneumoniae. Based on this result, we found that Galla Chinensis reduced the capsular polysaccharide biosynthesis in K. pneumoniae to help host immune system to eliminate the pathogen. For future clinical application, more studies to elucidate the active components and the mechanism exerted by Galla Chinensis are needed.
