TD/GC–MS analysis of volatile markers emitted from mono- and co-cultures of Enterobacter cloacae and Pseudomonas aeruginosa in artificial sputum
Introduction: Infections such as ventilator-associated pneumonia (VAP) can be caused by one or more pathogens. Current methods for identifying these pathogenic microbes often require invasive sampling, and can be time consuming, due to the requirement for prolonged cultural enrichment along with selective and differential plating steps. This results in delays in diagnosis which in such critically ill patients can have potentially life-threatening consequences. Therefore, a non-invasive and timely diagnostic method is required. Detection of microbial volatile organic compounds (VOCs) in exhaled breath is proposed as an alternative method for identifying these pathogens and may distinguish between mono- and poly-microbial infections. Objectives: To investigate volatile metabolites that discriminate between bacterial mono- and co-cultures. Methods: VAP-associated pathogens Enterobacter cloacae and Pseudomonas aeruginosa were cultured individually and together in artificial sputum medium for 24 h and their headspace was analysed for potential discriminatory VOCs by thermal desorption gas chromatography–mass spectrometry. Results: Of the 70 VOCs putatively identified, 23 were found to significantly increase during bacterial culture (i.e. likely to be released during metabolism) and 13 decreased (i.e. likely consumed during metabolism). The other VOCs showed no transformation (similar concentrations observed as in the medium). Bacteria-specific VOCs including 2-methyl-1-propanol, 2-phenylethanol, and 3-methyl-1-butanol were observed in the headspace of axenic cultures of E. cloacae, and methyl 2-ethylhexanoate in the headspace of P. aeruginosa cultures which is novel to this investigation. Previously reported VOCs 1-undecene and pyrrole were also detected. The metabolites 2-methylbutyl acetate and methyl 2-methylbutyrate, which are reported to exhibit antimicrobial activity, were elevated in co-culture only. Conclusion: The observed VOCs were able to differentiate axenic and co-cultures. Validation of these markers in exhaled breath specimens could prove useful for timely pathogen identification and infection type diagnosis.
2018
2019-07-18 08:21:55
1033
Bacteria, Enterobacter cloacae, Gas Chromatography-Mass Spectrometry, Infection, Pseudomonas aeruginosa, Volatile organic compounds
r6
Iain R.
White
70
Oluwasola
Lawal
70
Hugo
Knobel
70
Weda
Hans
70
Tamara M E
Nijsen
70
Royston
Goodacre
70
Stephen J
Fowler
70
Waqar M
Ahmed
70
Antonio
Artigas
70
Jonathan
Barnard-Smith
70
Lieuwe D
Bos
70
Marta
Camprubi
70
Luis
Coelho
70
Paul
Dark
70
Alan
Davie
70
Emili
Diaz
70
Gemma
Goma
70
Timothy
Felton
70
Jan H
Leopold
70
Pouline M P
van Oort
70
Pedro
Póvoa
70
Craig
Portsmouth
70
COBISS_ID
3
5419515
DOI
15
10.1007/s11306-018-1357-5
NUK URN
18
URN:SI:UNG:REP:U3BSB50K
Lawal2018_Article_TDGCMSAnalysisOfVolatileMarker.pdf
1354281
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2019-07-18 08:27:53
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Izvorni URL
2019-07-18 08:28:09