Highly specific differentiation ofmycobacterium avium subspec. paratuberculosis(MAP) in comparison to other mycobacteria using GC IMS-spectral analysis from headspace

Introducton: The Ion mobility spectrometry (IMS) is a highly sensitive method for detection of volatile organic compounds. There is no need for pre-analytical procedures in humidified air samples, i.e. exhaled air. The aim of the study was to prove the specificity of differentiation of different strains and subtypes of mycobacteria. Methods: Headspaces of agar and mycobacterial cultures were analysed. For comparison to MAP were used: mycobacterium avium avium, mycobacterium avium hominisuis, mycobacterium smegmatis, mycobacterium fortuitum. Using clusteranalysis and support vector machine the peaks were identified and compared to each other. The sensitivity and specificity was evaluated by Leave-One-Out cross validation discriminant analysis method. Results: 102 different clusters were detected. Many clusters represent the different relationship of different bacteria, domonstrating that for identification of specific bacteria a combination of clusters will be needed. Using more peaks the specificity for the identification of a certain germ will increase. Fig. 1: Example Boxplots of Cluster 39 and 48. Summary: Different bacteria species were possible to differentiate with 96% sensitivity and 84% specificity. The VOC-based detection of bacterial growth is highly specific and will be useful also for prevention of the risk of infection among staff.