Identification of microorganisms based on headspace analysis of volatile organic compounds by gas chromatography–mass spectrometry

Abstract

The identification of specific volatile organic compounds (VOCs) produced by microorganisms may assist in developing a fast and accurate methodology for the determination of pulmonary bacterial infections in exhaled air. As a first step, pulmonary bacteria were cultured and their headspace analyzed for the total amount of excreted VOCs to select those compounds which are exclusively associated with specific microorganisms. Development of a rapid, noninvasive methodology for identification of bacterial species may improve diagnostics and antibiotic therapy, ultimately leading to controlling the antibiotic resistance problem. Two hundred bacterial headspace samples from four different microorganisms (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Klebsiella pneumoniae) were analyzed by gas chromatography-mass spectrometry to detect a wide array of VOCs. Statistical analysis of these volatiles enabled the characterization of specific VOC profiles indicative for each microorganism. Differences in VOC abundance between the bacterial types were determined using ANalysis of VAriance-principal component analysis (ANOVA-PCA). These differences were visualized with PCA. Cross validation was applied to validate the results. We identified a large number of different compounds in the various headspaces, thus demonstrating a highly significant difference in VOC occurrence of bacterial cultures compared to the medium and between the cultures themselves. Additionally, a separation between a methicillin-resistant and a methicillin-sensitive isolate of S. aureus could be made due to significant differences between compounds. ANOVA-PCA analysis showed that 25 VOCs were differently profiled across the various microorganisms, whereas a PCA score plot enabled the visualization of these clear differences between the bacterial types. We demonstrated that identification of the studied microorganisms, including an antibiotic susceptible and resistant S. aureus substrain, is possible based on a selected number of compounds measured in the headspace of these cultures. These in vitro results may translate into a breath analysis approach that has the potential to be used as a diagnostic tool in medical microbiology.

Initial study of three different pathogenic microorganisms by gas chromatography-mass spectrometry

“…Another important point is that the percentage of the total area that the average peaks for 2,3-Pentandione, cis-Dihydro-α-terpinyl acetate, 1-Decyne, 1,3-Heptadiene-3-yne, 2,5-dimethyl Pyrazine, Ethyl butanoate and Cyclohexene,4-ethenyl covered were at least 15%; thus, they are remarkable VOCs for S. aureus . Some of the VOCs produced by S. aureus in the current study have been reported in other studies 34, 37 but some of them have not 28, 33 . The origin of all produced VOCs is not exactly known.…”

“…As previous studies have shown, organisms are able to produce either common or specific VOCs 33– 35 . In the current study, GC-MS was used to detect VOCs generated by three pathogenic organisms in the human respiratory tract.…”

“…Finding a non-invasive and rapid method for diagnosis of infectious agents is a subject of interest, so it has been investigated in several studies 33, 42– 45 . The current study showed that using SPME fiber and GC-MS for extraction and detection of VOCs allowed detection of more specific VOCs for the three pathogenic respiratory tract organisms, E. coli , S. aureus and C. albicans , which could be used as biomarkers for their identification.…”

Chopper-modulated gas chromatography electroantennography enabled using high-temperature MEMS flow control device

“…Various research disciplines, including environmental monitoring, biomedical diagnostics, entomology, fossil fuel exploration and food processing, have benefitted from GC technology [1][2][3][4][5] . Microfabrication technology has enabled important advancements in GC-related technologies.…”

Volatile-Sulfur-Compound Profile Distinguishes Burkholderia pseudomallei from Burkholderia thailandensis

“…This technique complements other rapid phenotyping methods such as MALDI-TOF MS for rapid culture characterization. It has been applied previously to more commonly encountered bacterial species (8-10) and used for their direct detection in exhaled breath samples (11). Production of DMS by marine algae is thought to act as a defense against oxidative stress (12) and induces apoptosis in malignant human showing the time-dependent trends that distinguish the two species.…”