Quorum sensing (QS) is the ability of some bacteria to detect and to respond to population density through signalling molecules. QS molecules are involved in motility and cell aggregation mechanisms in diseases such as sepsis. Few biomarkers are currently available to diagnose sepsis, especially in high-risk conditions. The aim of this study was the development of new analytical methods based on liquid chromatography-mass spectrometry for the detection and quantification of QS signalling molecules, including N-acyl homoserine lactones (AHL) and hydroxyquinolones (HQ), in biofluids. Biological samples used in the study were Pseudomonas aeruginosa bacterial cultures and plasma from patients with sepsis. We developed two MS analytical methods, based on neutral loss (NL) and product ion (PI) experiments, to identify and characterize unknown AHL and HQ molecules. We then established a multiple-reaction-monitoring (MRM) method to quantify specific QS compounds. We validated the HPLC-MS-based approaches (MRM-NL-PI), and data were in accord with the validation guidelines. With the NL and PI MS-based methods, we identified and characterized 3 and 13 unknown AHL and HQ compounds, respectively, in biological samples. One of the newly found AHL molecules was C12-AHL, first quantified in Pseudomonas aeruginosa bacterial cultures. The MRM quantitation of analytes in plasma from patients with sepsis confirmed the analytical ability of MRM for the quantification of virulence factors during sepsis.

群体感应（QS）是某些细菌通过信号分子检测并响应种群密度的能力。QS分子参与败血症等疾病的运动和细胞聚集机制。目前很少有生物标记物可用于诊断败血症，尤其是在高危条件下。这项研究的目的是开发基于液相色谱-质谱的新分析方法，用于检测和定量生物流体中QS信号分子，包括N-酰基高丝氨酸内酯（AHL）和羟基喹诺酮（HQ）。研究中使用的生物样品是铜绿假单胞菌败血症患者的细菌培养物和血浆。我们基于中性损失（NL）和产物离子（PI）实验开发了两种质谱分析方法，以鉴定和表征未知的AHL和HQ分子。然后，我们建立了多反应监测（MRM）方法来定量特定的QS化合物。我们验证了基于HPLC-MS的方法（MRM-NL-PI），数据符合验证准则。使用基于NL和PI MS的方法，我们分别在生物样品中鉴定和鉴定了3种和13种未知的AHL和HQ化合物。新发现的AHL分子之一是C12-AHL，最早在铜绿假单胞菌中定量细菌培养。对败血症患者血浆中的分析物进行MRM定量分析，证实了MRM对脓毒症中毒力因子进行定量分析的能力。