Identification of volatile organic compounds produced by bacteria using HS-SPME-GC-MS

The analysis of volatile organic compounds (VOCs) as a tool for bacterial identification is reported. Headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS) was applied to the analysis of bacterial VOCs with the aim of determining the impact of experimental parameters on the generated VOC profiles. The effect of culture medium, SPME fiber type and GC column were fully evaluated with the Gram-negative bacteria Escherichia coli and Klebsiella pneumoniae and the Gram-positive species Staphylococcus aureus. Multivariate analysis, including cluster analysis and principal component analysis, was applied to VOC data to determine whether the parameters under investigation significantly affected bacterial VOC profiles. Culture medium, and to a lesser extent, SPME fiber type, were found to significantly alter detected bacterial VOC profiles. The detected VOCs varied little with the polarity of the GC column. The results indicate that the generated bacterial VOC profiles need careful evaluation if they are to be used for clinical diagnostics. The whole process is limited by the need to grow the bacteria in broth (18 h) before extraction and analysis (63 min).