Trace element analysis of urine by ICP-MS/MS to identify urinary tract infection

摘要

Urinary tract infection (UTI) affects millions of people each year and is a major global public health issue. Understanding the milieu at the host-pathogen interface during UTI is critical to developing novel methods to diagnose and treat this ubiquitous infectious condition. The emerging field of metallomics, and more recently, urinary metallomics has provided exciting opportunities to explore the mechanisms associated with the uptake, transport and storage of trace elements in biological systems. Potential biomarkers found in urine may be used for screening, early diagnosis and treatment monitoring of important diseases, including UTI. In the present study, we use inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) to identify potential trace element biomarkers in human urine samples from 61 UTI patients and from 26 healthy volunteers. From 75 analytes evaluated, the 9 most promising elements were accurately determined in all 87 samples. Limits of detection (LODs) in the 0.9-100 ng L~(-1) range were calculated for Bi, Cs, Mo, Rb, Sb, Sn, Sr, V and Zn. The method's accuracy was evaluated by spike experiments, which provided recoveries in the 90.7-104.0% range for all analytes. Statistically significant differences (t-test at the 95% confidence level) between UTI and healthy samples were observed for Mo, Sb and V. The results show a trend with UTI samples presenting higher levels of Sb and lower levels of Mo and V compared with samples from healthy volunteers. For Sb, for example, all healthy urine samples presented concentrations below the LOD, while UTI samples had an average concentration of 1.1 μg L~(-1). For the first time, we demonstrate the potential of using Mo, Sb and V as urine biomarkers for UTI. Among these, Sb is particularly attractive because of its extremely low baseline levels in urine, which may represent superior sensitivity in detecting host reaction to infection.