Influenza A is a serious pathogen itself, but often leads to dangerous
co-infections in combination with bacterial species such as Streptococcus pyogenes. In comparison to classical biochemical methods, analysis of
volatile organic compounds (VOCs) in headspace above cultures can enable destruction free monitoring of metabolic processes in vitro. Thus, volatile
biomarkers emitted from
biological cell cultures and pathogens could serve for monitoring of
infection processes in vitro. In this study we analysed VOCs from headspace above (co)-infected human cells by using a customized sampling system. For investigating the
influenza A mono-
infection and the viral-bacterial
co-infection in vitro, we analysed VOCs from Detroit cells inoculated with influenza A virus and S. pyogenes by means of needle-trap micro-extraction (NTME) and gas chromatography mass spectrometry (GC-MS). Besides the determination of microbiological data such as cell count,
cytokines, virus load and bacterial load, emissions from cell medium, uninfected cells and bacteria mono-infected cells were analysed. Significant differences in emitted VOC concentrations were identified between non-infected and infected cells. After inoculation with S. pyogenes,
bacterial infection was mirrored by increased emissions of
acetaldehyde and
propanal.
N-propyl acetate was linked to
viral infection. Non-destructive monitoring of
infections by means of VOC analysis may open a new window for
infection research and clinical applications. VOC analysis could enable early recognition of pathogen presence and in-depth understanding of their etiopathology.