造成化膿性肝膿瘍及其他轉移性感染的 克雷伯氏肺炎桿菌菌株之基因體差異性

Abstract

由侵襲性克雷伯氏肺炎桿菌所造成的原發性肝膿瘍合併敗血症，目前已成為全球性的新興感染症。我們利用基因微陣列的方式，在侵襲性菌株中找尋到一段長約20 kb的染色體片段，並將其命名為kfu/PTS片段。此片段共涵蓋15個開放讀架，其中包括一組與鐵攝取有關的基因（kfuABC）、一組phosphoenolpyruvate sugar phosphotransferase system（PTS）和6個功能未知的開放讀架。這個片段多分佈於侵襲性菌株中(35/46)，而在非侵襲性菌株則分佈較少（19/98），統計分析兩者間有顯著的差異（p＜0.0001, Chi-Square test）。為了證實此長片段基因與細菌本身致病力的關係，我們設計了3組基因剔除菌株（ΔkfuABC, ΔORF7-9, ΔPTS），其中只有ΔkfuABC菌株與原生菌株比較，喪失對鼷鼠的致病力。進一步的實驗證明kfuABC基因組可幫助細菌在缺鐵的生長條件下與外界競爭鐵的來源。此外，我們發現kfu/PTS片段與另兩段與組織侵襲性有關的染色體片段（allS和magA）有極高的相關性（85％）；且臨床上能同時造成原發性肝膿瘍合併眼內炎或腦膜炎的菌株都共同包含此3個片段。因此，我們推測侵襲性克雷伯氏肺炎桿菌菌株間有顯著的遺傳差異，同時帶有此3個片段的基因型菌株和肝膿瘍與其他轉移性的併發症發生有強烈的相關性。這3個片段可以應用於臨床上作為快速診斷侵襲性感染菌株的方便指標。

Primary pyogenic liver abscess (PLA) with septic complication by Klebsiella pneumoniae is an emerging infectious disease. Using DNA microarray hybridization, we identified a 20-kb chromosomal region that contained 15 open-reading frames (ORFs), including an iron-uptake system (kfu), a phosphoenolpyruvate sugar phosphotransferase system (PTS), and 6 unknown ORFs. The region was more prevalent among tissue-invasive strains (35/46) than among noninvasive strains (19/98) (p＜0.0001, Chi-Square test). To test the role played by this region in pathogenesis, 3 different deletion mutants (NTUH-K2044 [Δkfu], K2044 [ΔORF7–9], and K2044 [ΔPTS]) were constructed. Only the ΔkfuABC mutants showed decreased virulence in mice, compared with the wild-type strain. An in vitro assay confirmed the involvement of kfu in iron acquisition. There was a high correlation rate (85%) between the kfu/PTS region and 2 tissue invasion–associated chromosomal regions (allS and magA). Moreover, all 3 regions were present in strains that caused PLA plus endophthalmitis or meningitis. Our results suggest that chromosomal heterogeneity is present in tissue-invasive K. pneumoniae strains. A genotype containing all 3 regions is strongly associated with PLA and metastatic infection. These regions may serve as convenient markers for the rapid diagnosis of emergent tissue-invasive strains.