Molecular analysis of volatile metabolites released specifically by Staphylococcus aureus and Pseudomonas aeruginosa

• Published in: BMC microbiology Vol. 12; no. 1; p. 113
• Main Authors: Filipiak, Wojciech, Sponring, Andreas, Baur, Maria Magdalena, Filipiak, Anna, Ager, Clemens, Wiesenhofer, Helmut, Nagl, Markus, Troppmair, Jakob, Amann, Anton
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 20.06.2012; BioMed Central; BMC
• Subjects: Adsorptive enrichment; Adult; Aged; Aged, 80 and over; Aldehydes; Analysis; Bacteria; Bacterial infections; Bacterial Infections - diagnosis; Bacterial Infections - microbiology; Bacterial pneumonia; Breath analysis; Breath Tests; Cell culture; Chromatography; Chronic obstructive pulmonary disease; Cystic fibrosis; Disease; Experiments; Female; Gas chromatography mass spectrometry (GCMS); Gas Chromatography-Mass Spectrometry; Health aspects; Humans; In vitro headspace sampling; Intensive care; Lung Diseases - diagnosis; Lung Diseases - microbiology; Male; Mass spectrometry; Medical research; Metabolites; Microbiology; Middle Aged; Mortality; Multibed sorption tubes; Organic compounds; Physiological aspects; Pneumonia; Pseudomonas aeruginosa; Pseudomonas aeruginosa - classification; Pseudomonas aeruginosa - metabolism; Standard deviation; Staphylococcus aureus; Staphylococcus aureus - classification; Staphylococcus aureus - metabolism; Staphylococcus aureus infections; Statistical analysis; Studies; Sulfur compounds; Thoracic surgery; Tuberculosis; Volatile metabolites; Volatile organic compounds (VOCs); Volatile Organic Compounds - analysis; Young Adult; Austria; Germany
• ISSN: 1471-2180; 1471-2180
• DOI: 10.1186/1471-2180-12-113

The routinely used microbiological diagnosis of ventilator associated pneumonia (VAP) is time consuming and often requires invasive methods for collection of human specimens (e.g. bronchoscopy). Therefore, it is of utmost interest to develop a non-invasive method for the early detection of bacterial infection in ventilated patients, preferably allowing the identification of the specific pathogens. The present work is an attempt to identify pathogen-derived volatile biomarkers in breath that can be used for early and non- invasive diagnosis of ventilator associated pneumonia (VAP). For this purpose, in vitro experiments with bacteria most frequently found in VAP patients, i.e. Staphylococcus aureus and Pseudomonas aeruginosa, were performed to investigate the release or consumption of volatile organic compounds (VOCs). Headspace samples were collected and preconcentrated on multibed sorption tubes at different time points and subsequently analyzed with gas chromatography mass spectrometry (GC-MS). As many as 32 and 37 volatile metabolites were released by S. aureus and P. aeruginosa, respectively. Distinct differences in the bacteria-specific VOC profiles were found, especially with regard to aldehydes (e.g. acetaldehyde, 3-methylbutanal), which were taken up only by P. aeruginosa but released by S. aureus. Differences in concentration profiles were also found for acids (e.g. isovaleric acid), ketones (e.g. acetoin, 2-nonanone), hydrocarbons (e.g. 2-butene, 1,10-undecadiene), alcohols (e.g. 2-methyl-1-propanol, 2-butanol), esters (e.g. ethyl formate, methyl 2-methylbutyrate), volatile sulfur compounds (VSCs, e.g. dimethylsulfide) and volatile nitrogen compounds (VNCs, e.g. 3-methylpyrrole).Importantly, a significant VOC release was found already 1.5 hours after culture start, corresponding to cell numbers of ~8*106 [CFUs/ml]. The results obtained provide strong evidence that the detection and perhaps even identification of bacteria could be achieved by determination of characteristic volatile metabolites, supporting the clinical use of breath-gas analysis as non-invasive method for early detection of bacterial lung infections.