Detektion von humanpathogenen Bakterien mittels Ionenmobilitätsspektrometrie im Headspace von Bakterienkolonien

Detection of human pathogenic bacteria by ion mobility spectrometry in the headspace of bacterial colonies

by Lena Kristina Hofmann
Doctoral thesis
Date of Examination:2019-09-25
Date of issue:2019-09-04
Advisor:PD Dr. Thorsten Perl
Referee:PD Dr. Thorsten Perl
Referee:Prof. Dr. Michael Weig
Persistent Address: http://dx.doi.org/10.53846/goediss-7611

 

 

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Abstract

English

Patients with infections, e. g. ventilator-associated pneumonia, have a high mortality. As the results of the infectiologist need 2-4 days to be ready, an adequate therapy begins delayed and the general condition of the patients get worse. This leads to a higher rate of mortality, a longer hospitalization and higher hospital costs. In this work it is examined if it’s possible to distinguish and identify P. aeruginosa, P. pneumoniae and S. aureus from each other based on their headspace volatiles with MCC-IMS. GC-MS was used as complement to identify more VOCs respectively to determine other substances.  The ion mobility-mass spectrometry is a well known method in analytical chemistry. Mass spectrometry is another method to identify pathogenetic germs. In several studies it was shown that different methods of mess spectrometry can identify and determine bacteria and fungi. The disadvantage is that the methods need big technical effort.  In this work it is used a multi capillary column coupled ion mobility-mass spectrometry, to differentiate the complex volatiles. The headspace of the pathogenic VOCs were pre-seperated  in the multi capillary column. A specific retention time results of each analyte. Further the sample was ionized in the IMS and it followed a second separating in an electrical field by mobility and by using a driftgas. Retention time and reduced ion mobility are necessary to determinate the volatile. The signal intensity is depending on the occurrence. After inoculation for 24 hours for each germ the measurement in MCC-IMS started. The measurements were in positive and negative polarization. The substances were named by their retention- and drifttime. The results show that differentiation and identifying by the specific volatile of P. aeruginosa, S. aureus and S. pneumoniae is possible. For P. aeruginosa was ethanol and one unknown substance (p_711_3) specific. Ethanol and two unknown (p_572_8; p_599_10) volatile were characteristic for S. aureus. S pneumoniae shows only one specific substance (p_572_8). The additional TD-GC-MS couldn`t identify the three unknown characteristic volatile of the MCC-IMS. Ethanol was identified by this method. Furthermore more volatile were identified: P. aeruginosa shows seven, S. aureus three and S. pneumoniae four other volatile.  The results show that MCC-IMS is a good method for analyzing metabolome. The MCC-IMS is a recommend alternative in diagnosis of complex gas mixtures in opposite to normal methods. It’s fast and reliable to identify and differentiate pathogenic germs.
Keywords: bacteria; ims; S. aureus; S. pneumoniae; S. aeruginosa; GC; headspace; volatile organic compound; multi capillary column
Schlagwörter: Ionenmobilitätspektrometrie; Gaschromatographie; Bakterien; VOC; Multikapillarsäule
 
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