Volatile biomarkers as identifiers for pathogenic oral bacteria

A study from the Department of Chemistry at the University of Helsinki shows that pathogenic oral bacteria can be identified and separated according to the volatile compounds they produce. In the future, volatile biomarkers can be used for detecting infections in both clinical and laboratory settings.

Volatile biomarkers are compounds that exist in gaseous form or easily change phase from liquid to gas. In the human body, they exchange between blood and the lungs, and consequently, can be detected from the exhaled breath. Examples of volatile compounds are malodorous sulfur compounds present in the morning breath or ethanol, which has been traditionally measured from the exhaled breath with a breathalyzer.

The aim of the research is finding new volatile biomarkers for pathogenic oral bacteria. Bacterial species responsible for periodontitis and other serious infections, such as abscesses, are the main subject of interest.

Oral infections are prevalent both in Finland and globally. Approximately 74 percent of Finnish adults have inflammation of the gum tissue, known as gingivitis, and 21 percent have already developed periodontitis, a disease destroying the supportive tissues around teeth. Oral infections can also cause sepsis, if pathogenic bacteria are able to enter the bloodstream in large amounts, for example, through an abscess. Furthermore, oral infectious diseases have been linked to increased cardiovascular risk diabetes. Early diagnosis and treatment significantly decrease the risk for developing a serious oral infection. The detection and identification of pathogens via volatile compounds, whether from human exhaled breath or a culture, would be a quick and cost-effective diagnostics method for oral infections.

In the recent Nature Scientific Reports publication, the focus is identifying the volatile compounds produced by the selected oral bacteria and measuring the capacity in which these bacteria are able to produce certain compounds. The analysis was done with a combination of two mass spectrometric methods, which provide sensitive, real-time information about the concentrations of the volatiles, as well as their concrete identification.

According to the results, the studied oral bacteria can be distinguished based on the volatiles produced. In addition, the real-time measurements suggest that bacteria produce distinct compounds in different phases of their lifecycle. Certain compounds are connected to the active growth of the bacterial cells and others to cell death. This knowledge could be used, for example, to evaluate the progress of antibiotic treatment, if the volatiles connected to bacterial cell death are increased in the exhaled breath of the patient.

Next, the bacterial findings reported in the recent publication are combined with human breath measurements. The final goal is to develop a breath test for detecting and monitoring oral infections. In the future, analysis of volatile biomarkers could be a quick complimentary method for basic microbiological laboratory tests, such as bacterial culturing. Furthermore, infections could be detected non-invasively in the future by measuring volatile biomarkers from the human exhaled breath. Reliable methods based on the analysis of volatile compounds could also be further develop for viral and fungal infections as well.

Lead author of the publication is Doctoral Student Kajsa Roslund from the University of Helsinki. Other members of the research group: Dr. Doc. Markus Metsälä (Department of Chemistry, UH), Dr. Doc. Pirkko Pussinen (Oral and Maxillofacial Diseases, UH & HUS), Dr. Markku Lehto (Folkhälsan Institute of Genetics and Abdominal Center, UH & HUS), Dr. Doc. Kari Hartonen (Department of Chemistry, UH), Prof. Lauri Halonen (Department of Chemistry, UH) ja Prof. Per-Henrik Groop (Folkhälsan Institute of Genetics and Abdominal Center, UH & HUS).

Reference:
Roslund, K., Lehto, M., Pussinen, P. et al. Identifying volatile in vitro biomarkers for oral bacteria with proton-transfer-reaction mass spectrometry and gas chromatography–mass spectrometry. Scientific Reports. 11, 16897 (2021). https://doi.org/10.1038/s41598-021-96287-7

More Information:
Kajsa Roslund, kajsa.roslund@helsinki.fi, phone +358 40 358 9835