Molecular analysis of volatile metabolites released specifically by staphylococcus aureus and pseudomonas aeruginosaReport as inadecuate




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BMC Microbiology

, 12:113

First Online: 20 June 2012Received: 24 February 2012Accepted: 20 June 2012DOI: 10.1186-1471-2180-12-113

Cite this article as: Filipiak, W., Sponring, A., Baur, M.M. et al. BMC Microbiol 2012 12: 113. doi:10.1186-1471-2180-12-113

Abstract

BackgroundThe 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.

ResultsHeadspace 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*10 CFUs-ml.

ConclusionsThe 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.

KeywordsVolatile organic compounds VOCs Gas chromatography mass spectrometry GCMS Breath analysis In vitro headspace sampling Adsorptive enrichment Multibed sorption tubes Volatile metabolites Staphylococcus aureus Pseudomonas aeruginosa AbbreviationsVAPVentilator associated pneumonia

ICUIntensive care unit

VOCsVolatile organic compounds

VSCsVolatile sulfur-containing compounds

VNCsVolatile nitrogen-containing compounds

CFUColony forming units

ODOptical density

GC-MSGas chromatography mass spectrometry

SIFT-MSSelected ion flow tube mass spectrometry

PTR-MSProton transfer reaction mass spectrometry

ENElectronic nose

2-AA2-aminoacetophenon

CFCystic fibrosis

BALBronchoalveolar lavage

pptvPart per trillion per volume corresponding to the ratio of 1:10-12

ppbvPart per billion per volume corresponding to the ratio of 1:10-9

ppmvPart per million per volume corresponding to the ratio of 1:10-6

TICTotal ion chromatogram

SIMSelected ion monitoring

MeSHMethanethiol

DMSDimethyl sulfide

DMDSDimethyl disulfide

DMTSDimethyl trisulfide

SPMESolid phase microextraction

LODLimit of detection

MEPMethylerythritol phosphate

COPDChronic obstructive pulmonary disease

SDStandard deviation.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2180-12-113 contains supplementary material, which is available to authorized users.

Wojciech Filipiak, Andreas Sponring contributed equally to this work.

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Author: Wojciech Filipiak - Andreas Sponring - Maria Magdalena Baur - Anna Filipiak - Clemens Ager - Helmut Wiesenhofer - Markus N

Source: https://link.springer.com/







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