克雷伯氏肺炎桿菌基因型在肝膿瘍致病機轉的角色：病例對照研究

Role of Klebsiella pneumoniae genotypes in pathogenesis of pyogenic liver abscess: A case-control study

謝汶娸(Wen-Chi Hsieh)

指導教授 ： 方啟泰

國立臺灣大學/公共衛生學院/流行病學與預防醫學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.11158

摘要

背景
摘要
克雷伯氏肺炎桿菌 (Klebsiella pneumoniae) 肝膿瘍 (pyogenic liver abscess, PLA) 是台灣重要的社區感染症。K. pneumoniae PLA 致病機轉研究有兩個層面, 一為細菌毒力因子,另一則是宿主潛伏疾患。目前已知克雷伯氏肺炎桿菌的毒力 因子包括:莢膜 (CPS) 與脂多醣 (LPS)(有多種基因型)、胞外多醣合成轉錄促 進因子 (rmpA/A2) 和捕鐵系統 (iron-acquisition system)—Kfu 與 Yersiniabactin 位 於細菌染色體上;Aerobactin 與 Salmochelin 則位於細菌大型毒力質體 pVLP。先前 研究也發現糖尿病、肝膽疾病以及惡性腫瘤等宿主疾患是不分菌種 PLA 的危險因 子。然而,到目前為止尚無針對 K. pneumoniae PLA 危險因子的研究,克雷伯氏肺 炎桿菌致病性相關基因型在 K. pneumoniae PLA 的角色目前仍不清楚,且細菌毒力 因子與宿主疾患之間是否在 K. pneumoniae PLA 致病機轉中有協同作用也尚待釐清。
研究目的
本研究目的為分析克雷伯氏肺炎桿菌致病性相關基因型在 K. pneumoniae PLA 致病機轉所扮演的角色,並且釐清克雷伯氏肺炎桿菌致病性相關基因型與宿主疾 患在肝膿瘍致病機轉上的生物學交互作用。
方法
本研究是一以醫院為本的病例對照研究。收集 2006-2011 期間在台大醫院新診 斷的社區感染 K. pneumoniae PLA 病患作為病例組,共 90 例。將同時段內,在入 院前或入院時分離出克雷伯氏肺炎桿菌,但沒有發展為 PLA 的病患作為對照組, 共有 179 例。我們使用特異性聚合酶連鎖反應引子對從病例組與對照組分離出來 的菌株進行基因型分析,包括 CPS 和 LPS (含 OPS 與 Core 兩部分) 基因分型以及 毒力因子 rmpA/A2 和四個捕鐵系統的偵測。另一方面,查閱病患的醫療記錄,系統性地收集所有病患的基本資料以及相關病史。資料分析時使用邏輯斯迴歸分析克雷伯氏肺炎桿菌肝膿瘍的危險因子,並以 PRISM 指標檢定克雷伯氏肺炎桿菌基 因型與宿主疾患間的生物交互作用。
結果
本研究共納入 90 位病例患者以及 179 位對照患者。在病例組中,K1 (59%) 與 K2 (21%) 是最常見的兩種 CPS 基因型;O1 (93%) 與 core 1 (81%) 則是最常見的 LPS 基因型。絕大多數造成 PLA 的病例組菌株都帶有 rmpA/A2 (96%) 基因以及捕 鐵系統 kfu (64%)、irp2 (87%)、iucB (93%)、iroN (94%)。基因型 CPS、LPS 與捕鐵 系統有很強的相關性。病例組或對照組病人原本就罹患糖尿病 (47.8% vs. 55.3%) 或肝膽疾病 (38.9% vs. 45.8%) 的比例都非常高。多變項邏輯斯回歸顯示下列細菌 基因型:K1: O1: core 1: kfu+ irp2+ (adjusted OR=6.1, P<0.001)、K2: O1: core 2: irp2+ (adjusted OR=5.9, P=0.006)、pVLP: iucB+ iroN+ rmpA/A2+ (adjusted OR=8.5, P<0.001) 與 pVLP: iucB+/iroN+ (adjusted OR=6.8, P=0.028) 是造成 K. pneumoniae PLA 的獨立 危險因子,但糖尿病、肝膽疾病與惡性腫瘤等宿主疾患則不是獨立危險因子。 PRISM 檢定結果顯示基因型為 K1: O1: core 1: kfu+ irp2+ 的克雷伯氏肺炎桿菌菌株 可以在不需有糖尿病的情況下獨立造成 K. pneumoniae PLA (PRISM=0.403, P= 0.031)。然而,糖尿病可能與基因型 K2: O1: core 2: irp2+ (PRISM=2.073, P=0.470) 以 及 K2: O1: core 2: irp2− (PRISM=1.677, P=0.501) 在 K. pneumoniae PLA 的致病機轉中有協同交互作用存在。
結論
本研究證實,克雷伯氏肺炎桿菌致病性相關基因型,包括 K1: O1: core 1: kfu+ irp2+、K2: O1: core 2: irp2+、pVLP: iucB+ iroN+ rmpA/A2+ 與 pVLP: iucB+/iroN+,在 K. pneumoniae PLA 的致病機轉中扮演極重要的角色。另外,基因型為 K1: O1: core 1: kfu+ irp2+ 的克雷伯氏肺炎桿菌菌株可獨立造成 K. pneumoniae PLA 不需宿主有 糖尿病;但糖尿病與兩種 K2 基因型 K2: O1: core 2: irp2+ 與 K2: O1: core 2: irp2− 在 K. pneumoniae PLA 的致病機轉中可能有協同交互作用存在。

關鍵字

克雷伯氏肺炎桿菌 ； 細菌性肝膿瘍 ； 基因型 ； 致病機轉 ； 病例對照研究

並列摘要

Background
Klebsiella pneumoniae pyogenic liver abscess (PLA) is a community-acquired infectious disease that is endemic in Taiwan. Previous studies have suggested that both host factors and bacterial virulence factors could be involved in the pathogenesis of K. pneumoniae PLA. In K. pneumoniae, pathogenicity-associated genotypes include capsular polysaccharides (CPS), lipopolysaccharides (LPS), rmpA/A2, and iron acquisition systems: the Kfu iron acquisition system and yersiniabactin are located on the bacterial chromosome, whereas aerobactin and salmochelin are located on the large virulence plasmid pVLP.
At the present time, no studies have been performed to examine the risk factors for K. pneumoniae PLA. The role of K. pneumoniae genotypes in the pathogenesis of K. pneumoniae PLA remains unclear. The pathogenesis mechanism—especially the interaction between bacterial virulence and host factors—has not yet been clarified in humans.
Aims
The aim of this study was to determine the role of K. pneumoniae genotypes in the pathogenesis of K. pneumoniae PLA and to determine the biological interaction of K. pneumoniae with underlying diseases in the host.
Methods
This is a hospital-based case-control study. New-onset community-acquired K.
pneumoniae PLA cases diagnosed at National Taiwan University Hospital (NTUH)
from 2006-2011 were included. The controls were patients with community-acquired K. pneumoniae isolates who did not develop PLA during the same period. We conducted PCR genotyping of CPS, LPS O antigen and core of K. pneumoniae isolates collected from cases and controls using specific primers that have been validated with WHO reference strains. We also detected the presence of rmpA/A2 and four pathogenicity islands encoding iron acquisition systems. Information on the patients’ underlying diseases was obtained by reviewing medical records. Logistic regression was used to analyze the risk factors for PLA. Further, we used the peril ratio index of synergy based on multiplicativity (PRISM) to quantify the biological interaction between KP genotypes and underlying host disease.
Results
A total of 90 K. pneumoniae PLA cases and 179 controls were included in this study. The most common CPS genotype among the K. pneumoniae PLA cases was K1 (59%), followed by K2 (21%). The most common LPS genotype among the cases was O1 (93%), and core 1 (81%). The majority of K. pneumoniae that caused PLA carried rmpA/A2 (96%) and the iron acquisition systems kfu (64%), irp2 (87%), iucB (93%), and iroN (94%). Diabetes mellitus and hepatobiliary disease were common in both case patients and control patients (47.8% vs. 55.3% and 38.9% vs. 45.8%, respectively). There were strong correlations among the genotypes of CPS, LPS and the presence of iron acquisition systems. Multiple logistic regression analysis showed that K1: O1: core 1: kfu+ irp2+ (adjusted OR=6.1, P<0.001), K2: O1: core 2: irp2+ (adjusted OR=5.9, P=0.006), pVLP: iucB+ iroN+ rmpA/A2+ (adjusted OR=8.5, P<0.001), and pVLP: iucB+/iroN+ (adjusted OR=6.8, P=0.028) were independent risk factors for K.
pneumoniae PLA, while DM, HBD and malignancy were not independent factors.
Pathogen-host interaction analysis indicated that the K. pneumoniae strains K1: O1: core 1: kfu+ irp2+ (PRISM=0.403, P=0.031) and pVLP: iucB+ iroN+ rmpA/A2+ (PRISM=0.798, P=0.176) have the potential to cause PLA independent of host DM, while DM may synergistically interact with genotypes K2: O1: core 2: irp2+ (PRISM=2.073, P=0.470) and K2: O1: core 2: irp2− (PRISM=1.677, P=0.501) in the pathogenesis of K. pneumoniae PLA.
Conclusions
The present study demonstrated that several K. pneumoniae genotypes including K1: O1: core 1: kfu+ irp2+, K2: O1: core 2: irp2+, pVLP: iucB+ iroN+ rmpA/A2+, and pVLP: iucB+/iroN+ play a predominant role in the pathogenesis of K. pneumoniae PLA. K. pneumoniae strains with genotypes K1: O1: core 1: kfu+ irp2+ and pVLP: iucB+ iroN+ rmpA/A2+ can cause PLA independently. DM may synergistically interact with genotypes K2: O1: core 2: irp2+ and K2: O1: core 2: irp2− in the pathogenesis of K. pneumoniae PLA.

並列關鍵字

Klebsiella pneumoniae ； Pyogenic liver abscess ； Genotypes ； Pathogenesis ； Case-control study

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