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Gewählte Master / Diploma Thesis:

Dagmar Dattler (2011): Vergleich von Standards zur Antibiotikaresistenz-Bestimmung bei Laktobazillen und Charakterisierung von Antibiotikaresistenzen mithilfe eines DNA-Microarray.
Master / Diploma Thesis - Institut für Lebensmittelwissenschaften, BOKU-Universität für Bodenkultur, pp 184. UB BOKU obvsg

Data Source: ZID Abstracts
Lactic acid bacteria (LAB) have been used for hundreds of years in foodproducts, giving them the GRAS status. However, in recent years concerns about a possible transmission of transferable antibiotic resistances from intestinal LAB to pathogens have been rising. Thus, the absence of transferable resistance genes has become a fundamental requirement for starter cultures, probiotics and probiotoc feed supplements. Consequently, the development of standardized methods for LAB regarding transferable resistance genes is a major subject to perform this analysis in a solid and comparable way. In this work, a comparison between two standards for the phenotypic assay of non-enterococcal LABs and bifidobacteria is drawn. For this purpose, the susceptibility of 22 Lactobacillus strains to different classes of antibiotics has been analysed, following the ISO 10932/ IDF 233 (2010) standard and the CLSI guideline M45-A using the broth-microdilution method. For each strain and antibiotic combination, the minimal inhibitory concentration (MIC) is detected, using a set of three independent trials. First, the results are used for determining the repeatability. Secondly an assigment of the strains into the categories of "`sensitive"' or "`resistant"' is made. Additionally, the performance of growth under the given conditions is evaluated. Furthermore, the utilizability of the microarray AMR+ve (Identibac) for the analysis of bifidobacteria, pediococci, enterococci and lactobacilli is tested. In addition to the calculation of resistance data, experiments regarding the reusability of the microarray are carried out. Comparing the two standards, the ISO/IDF standard performs very well considering the repeatability and growth of all 22 tested Lactobacillus strains. In contrast, the CLSI guideline shows deficiencies, as only 11 of the 22 strains have adequate growth and the repeatability also falls behind that of the ISO/IDF standard, still performing in a satisfying way. A comparison of resistance gene data from microarrays with phenotypic data of two enterococcal strains confirms the microarray results. The experimental reuse of microarrays has been successful and provides reliable und useful data.

Beurteilende(r): Kneifel Wolfgang
1.Mitwirkender: Domig Konrad
2.Mitwirkender: Mayrhofer Sigrid

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