Abstract
Introduction
Volatile organic compounds (VOCs) are increasingly studied as potential biomarkers for various applications, such as diagnosis of diseases or detection of bacterial growth. In a study with Mycobacterium avium subsp. paratuberculosis (MAP) as model organism, we investigated if bacterial growth in in vitro cultures can be detected by VOC analysis already after 1 week of cultivation.
Methods
The headspace of MAP in vitro cultures was analyzed one week after inoculation with a GC-differential-ion-mobility-spectrometer (SIONEX). For comparison, culture media with no bacterial growth were included. Headspace was collected with a disposable PTFE tube. The spectra were analyzed by a statistical program based on cluster analysis.
Results
Cluster analysis resulted in 160 independent clusters. The headspace of bacterial in vitro cultures showed highly significant differences (p<0.001) to the headspace of culture media without growth for 10 of the 160 clusters. A cross-validated discriminant analysis resulted in 100 per cent sensitivity and 100 per cent specificity for classification of positive and negative samples.
Discussion
The study showed that VOC analysis can be a very fast and reliable method to detect bacterial growth in in vitro cultures. For MAP, growth can [KH1] be detected just one week after inoculation, which is much faster than currently used methods which take at least 4 to 6 weeks.
- © 2014 ERS