PDF(Pubmed)
Abstract：
Legionella spp. are Gram-negative bacteria that inhabit freshwater environments representing a serious risk for human health. Legionella pneumophila (Lp) is the species most frequently responsible for a severe pneumonia known as Legionnaires\' disease. Lp consists of 15 serogroups (Sgs), usually identified by monoclonal or polyclonal antibodies. With regard to Lp serogrouping, it is well known that phenotyping methods do not have a sufficiently high discriminating power, while genotypic methods although very effective, are expensive and laborious. Recently, mass spectrometry and infrared spectroscopy have proved to be rapid and successful approaches for the microbial identification and typing. Different biomolecules (e.g., lipopolysaccharides) adsorb infrared radiation originating from a specific microbial fingerprint. The development of a classification system based on the intra-species identification features allows a rapid and reliable typing of strains for diagnostic and epidemiological purposes. The aim of the study was the evaluation of Fourier Transform Infrared Spectroscopy using the IR Biotyper® system (Bruker Daltonik, Germany) for the identification of Lp at the serogroup (Sg) level for diagnostic purposes as well as in outbreak events. A large dataset of Lp isolates (n = 133) and ATCC reference strains representing the 15 Lp serogroups were included. The discriminatory power of the instrument\'s classifier, was tested by Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA). All isolates were classified as follows: 12/133 (9.0%) as Lp Sg1 and 115/133 (86.5%) as Lp Sg 2-15 (including both ATCC and environmental Lp serogroup). Moreover, a mis-classification for 2/133 (1.5%) isolates of Lp Sg 2-15 that returned as Lp Sg1 was observed, and 4/133 (3.0%) isolates were not classified. An accuracy of 95.49% and an error rate of 4.51% were calculated. IR Biotyper® is able provide a quick and cost-effective reliable Lp classification with advantages compared with agglutination tests that show ambiguous and unspecific results. Further studies including a larger number of isolates could be useful to implement the classifier obtaining a robust and reliable tool for the routine Lp serogrouping. IR Biotyper® could be a powerful and easy-to-use tool to identify Lp Sgs, especially during cluster/outbreak investigations, to trace the source of the infection and promptly adopt preventive and control strategies.
摘要：
军团菌属。是革兰氏阴性细菌，生活在淡水环境中，对人类健康构成严重威胁。嗜肺军团菌(Lp)是最常引起称为军团菌病的严重肺炎的物种。Lp由15个血清群(Sgs)组成，通常通过单克隆或多克隆抗体鉴定。关于Lp血清组配，众所周知，表型鉴定方法没有足够高的辨别能力，虽然基因型方法非常有效，既昂贵又费力。最近,质谱和红外光谱已被证明是快速和成功的微生物鉴定和分型的方法。不同的生物分子(例如，脂多糖）吸收源自特定微生物指纹的红外辐射。基于种内识别特征的分类系统的开发允许用于诊断和流行病学目的的菌株的快速和可靠的分型。研究的目的是使用IRBiotyper®系统（BrukerDaltonik，德国）用于诊断目的和爆发事件中的血清群（Sg）水平的Lp鉴定。包括代表15个Lp血清群的Lp分离株（n=133）和ATCC参考菌株的大数据集。仪器分类器的鉴别力，通过主成分分析(PCA)和线性判别分析(LDA)进行检验。所有分离株分类如下：12/133（9.0％）为LpSg1，115/133（86.5％）为LpSg2-15（包括ATCC和环境Lp血清群）。此外，观察到以LpSg1返回的LpSg2-15的2/133（1.5％）分离株的错误分类，和4/133（3.0％）分离株未分类。计算精度为95.49％，误差率为4.51％。IRBiotyper®能够提供快速且具有成本效益的可靠Lp分类，与显示模糊和非特异性结果的凝集测试相比具有优势。包括大量分离物的进一步研究可用于实施分类器,从而获得用于常规Lp血清分组的稳健且可靠的工具。IRBiotyper®可能是一个功能强大且易于使用的工具来识别LpSgs，特别是在集群/疫情调查期间，追踪感染源，并及时采取预防和控制策略。
