- 學位論文
莢膜分解酶治療克雷伯氏肺炎桿菌感染之小鼠模式
Utilization of capsule depolymerase as a treatment for Klebsiella Pneumoniae infection in mice
摘要
近年來，克雷伯氏肺炎桿菌造成的社區侵襲性原發性肝膿瘍成為了全球性的新興感染症。克雷伯氏肺炎桿菌菌體外的莢膜是重要的致病因子之一，可以抵抗宿主免疫細胞吞噬作用以及補體毒殺機制，而在台灣造成原發性肝膿瘍以K1、K2莢膜血清型最為常見，充分顯示莢膜型和致病力的相關性。克雷伯氏肺炎桿菌菌株的多重抗藥性問題日趨嚴重，例如Extended-spectrumβ-lactamase(ESBL)基因及Carbapenem-resistant Klebsiella pneumoniae(CRKP)。先前本實驗室已經找到能夠專一性感染K1 莢膜型菌株的噬菌體NTUH-K2044-K1-1 並具有全基因體定序，從中找到一為K1 莢膜分解酶的基因產物。本研究欲評估莢膜分解酶治療效果，因此接著篩選出出感染K2 莢膜型菌株的噬菌體1611E-K2-1 並從中找出K2 莢膜分解酶基因，利用基因重組技術大量表現純化出K1、K2 莢膜分解酶並證實對小鼠不具毒性，以腹腔注射感染K1、K2 莢膜型菌株的小鼠在感染後1 小時內接受單劑莢膜分解酶（25 μg）治療可提高87.5%（K1）或100%（K2）的存活率。目前將莢膜分解酶療法擴展至多重抗藥性菌株感染的治療，實驗室統計台大、長庚、成大和榮總四家醫院的CRKP 臨床菌株發現有集中於K64 莢膜型的現象。欲模擬臨床上易感染多重抗藥性菌株之免疫不全病人族群，利用Cyclophosphamide 建立免疫不全小鼠模式，以腹腔注射感染K64 莢膜型菌株後1 小時接受單劑K64 莢膜分解酶（150 μg）進行治療，仍可成功提高62.5%的存活率。因此，基因表現之莢膜分解酶應可作為傳統抗生素之外治療克雷伯氏肺炎桿菌感染的替代療法。
並列摘要
Community-acquired pyogenic liver abscess (PLA) caused by Klebsiella pneumoniae has become an emerging infectious disease. The capsule of K. pneumoniae is an important virulence factor, which can keep bacteria from phagocytosis and complement mediated lysis. Previous studies reported K1 and K2 were prevalent capsular serotypes of strains causing PLA in Taiwan. Multi-drug resistances of K. pneumoniae including Extended-spectrumβ-lactam resistance and Carbapenem-resistance Klebsiella pneumoniae (CRKP) are urgent global issues. Phage NTUH-K2044-K1-1 and its capsule depolymerase which were both specific to K1 capsule were identified in our previous study. Here, we isolated a phage 1611E-K2-1 shown to infect K2 strains and identified its K2 capsule depolymerase. Intraperitoneal administration of a single dose of 25 ug K1 or K2 capsule depolymerase at 1h after intraperitoneal infection of K. pneumoniae K1 or K2 strain could enhance 87.5 %(K1) or 100 %(K2) survival rate, respectively. We further tested capsule depolymerase treatment of multi-drug resistant (MDR) K. pneumoniae infection. We observed the most prevalent capsular type of CRKP from NTUH, CGUH, NCKUH, and VGH was K64. The efficacy of K64 capsule depolymerase treatment in cyclophosphamide-treated mice mimicing the immune-compromised patients infected with MDR K. pneumoniae was evaluated. Intraperitoneal administration of a single dose of 150 ug K64 capsule depolymerase at 1h after intraperitoneal infection of K. pneumoniae K64 strain also improve 62.5 % survival. Therefore, capsule depolymerase treatment is a potential therapy for K. pneumoniae infection alternative to conventional antibiotics treatment.