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Candida albicans is one of the most frequent causes of fungal infections in humans. Significant correlation between candiduria and invasive candidiasis has previously been described. The existing diagnostic methods are often time-consuming, cost-intensive and lack in sensitivity and specificity. In this study, the profile of low-molecular weight volatile compounds in the headspace of C. albicans-urine suspensions of four different fungal cell concentrations compared to nutrient media and urine without C. albicans was determined using proton-transfer reaction mass spectrometry (PTR-MS). At fungal counts of ≥1.5 × 10(5) colony forming units (CFU)/ml signals at 45, 47 and 73 atomic mass units (amu) highly significantly increased. At fungal counts of <1.5 × 10(5) CFU/ml signals at 47 and 73 amu also increased, but only at 45 amu a statistically significant increase was seen. Time course alterations of signal intensities dependent on different cell concentrations and after addition of Sabouraud nutrient solution were analysed. Recommendations for measurement conditions are given. Our study is the first to describe headspace profiling of C. albicans-urine suspensions of different fungal cell concentrations. PTR-MS represents a promising approach to rapid, highly sensitive and non-invasive clinical diagnostics allowing qualitative and quantitative analysis.

The theoretical use of mass spectrometric profiling of low-molecular-weight volatile compounds, as one possible method to non-invasively and rapidly diagnose a variety of diseases, such as cancer, infection, and metabolic disorders has greatly raised the profile of this technique over the last ten years. Despite a number of promising results, this technique has not been introduced into common clinical practice yet. The use of mass spectrometric profiling of exhaled air is particularly hampered by various technical problems and basic methodological issues which have only been partially overcome. However, breath analysis aside, recently published studies reveal completely new ideas and concepts on how to establish fast and reliable diagnosis by using this valuable tool. These studies focussed on the headspace screening of various bodily fluids and sample fluids obtained during diagnostic procedures, as well as microbial cell cultures and demonstrated the vast diagnostic potential of this technique in a wide variety of settings, predominantly in vitro. It is the aim of the present review to discuss the most commonly detected low-molecular-weight volatile compounds and to summarize the current potential applications, latest developments and future perspectives of this promising diagnostic approach.

The identification of bacteria by using conventional microbiological techniques can be very time-consuming and circumstantial. In contrast, the headspace screening of bacterial cultures by analyzing their emitted volatile compounds using mass spectrometry might provide a novel approach in diagnostic microbiology. In the present study different strains of Escherichia coli, Klebsiella, Citrobacter, Pseudomonas aeruginosa, Staphylococcus aureus, and Helicobacter pylori were investigated. The volatile compounds emitted by these bacteria in vitro were analyzed using proton-transfer-reaction mass spectrometry, which allows rapid and sensitive measurement. The detected patterns of volatile compounds produced by the investigated bacteria were compared and substantial differences regarding both quantity and quality were observed. In conclusion, the present study is the first to describe headspace screening of bacterial cultures as a potential diagnostic approach in medical microbiology.

Recently, increased interest has focused on the diagnostic potential of volatile organic compounds (VOC) exhaled in human breath as this substance group has been conjectured in indoor air quality and disease screening. Proton transfer reaction-mass spectrometry (PTR-MS) has been established as a new tool for a rapid determination of exhaled air profile. However, no investigations have been carried out into the profile of exhaled air as determined by PTR-MS. Therefore, it was the aim of the present study to determine the profile of exhaled breath in a field survey enrolling 344 persons. Analysis was performed using PTR-MS. No significant correlations with age, blood pressure, and body mass index could be observed with any molecular mass. The present study delineates possible reference values for PTR-MS investigations into exhaled air profile. In conclusion, the present study was the first to delineate mass spectrometric characteristics of an average patient sample as possible reference values.

Smoking is the most important single risk factor in current public health. Surveillance of exposure to tobacco smoke may be accomplished using environmental monitoring or in-vivo tests for smoking biomarkers. Acetonitrile exhaled in human breath has been described as a potential marker mirroring recent smoking behavior. The aim of this study was to determine exhaled acetonitrile levels in a sample of 268 volunteers (48 smokers, 220 non-smokers) attending a local health fair. Breath specimens were collected into inert sample bags, with parallel collection of ambient air. Subsequently, all samples were analysed using proton transfer reaction-mass spectrometry (PTR-MS). Smokers had elevated levels of exhaled acetonitrile compared with non-smokers (p<0.001). Analysis using the receiver-operating-characteristic curve demonstrated that smoking can be predicted with a sensitivity of 79% and a specificity of 91%, using a cut-off concentration of 20.31 parts per billion of acetonitrile. This first field survey of exhaled acetonitrile in a large group of test persons demonstrates the feasibility of a rapid and non-invasive test for recent exposure to tobacco. We conclude that analysis of exhaled-breath acetonitrile may serve as a method of determining recent active smoking behaviour.

Abstract: Background:: The diagnosis of many gastro-intestinal diseases is difficult and can often be confirmed only by using invasive diagnostic means. In contrast, the headspace screening of fluid obtained from the gut during colonoscopy and the analysis of exhaled air may be a novel approach for the diagnosis of these diseases. Materials and methods:: The screening was performed by using proton transfer reaction-mass spectrometry (PTR-MS) which allows rapid and sensitive measurement. Fluid samples obtained from the gut during colonoscopy were collected from 76 and breath samples from 70 subjects. Mass spectra of healthy controls were created. Afterwards these spectra were compared with those of patients suffering from inflammatory bowel diseases (IBD; Crohn''s disease and ulcerative colitis; n =10) and irritable bowel syndrome (IBS; n =7). Results:: Significant differences in the mass spectra could be observed both in the headspace of the fluid and in the exhaled air comparing patients with healthy controls. Conclusions:: This study is the first describing headspace screening of fluid obtained from the gut during colonoscopy, possibly presenting a novel diagnostic tool in the differential diagnosis of gastro-intestinal diseases. [Copyright &y& Elsevier]