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DDI - Teses de doutoramento

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http://hdl.handle.net/10400.18/24

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Browsing DDI - Teses de doutoramento by Subject "Animals"

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  • Assessing antibiotic resistance in Gram negative bacteria from animals and the wider environment
    Publication . Jones-Dias, Daniela; Caniça, Manuela; Nogueira, Isabel
    The alarming increase in the levels of antibiotic resistant bacteria in clinical practice launched the call for a broader understanding of this event. This Ph.D. thesis aimed to unravel the main mobile antibiotic resistance determinants circulating in Gram negative bacteria from non-human sources, showing the contribution of mobile genetic elements for the overall process. The susceptibility and molecular epidemiological studies performed on different collections of bacterial isolates showed the predominance of multidrug resistant Escherichia coli in animals of different origins, soil and vegetables. E. coli and other species of Gram negative bacteria were related with carriage of diverse antibiotic resistance genes [e.g. blaCTX-M-1, blaCTX-M-15, blaCMY-2, blaGES-11, qnrS1, aac(6’)-Ib-cr, strAB, tet, drfA, aadA, mcr-1] that were associated with a transferable genetic support. Indeed, an assortment of mobile genetic elements (e.g. IncI1 and IncF plasmids, ISEcp1 insertion sequences, Tn402 and Tn7 transposons and class 1, 2 and 3 integrons) was detected in the genetic proximity of those antibiotic resistance genes, suggesting their profound involvement, not only in interspecies dispersion, but also in the movement of the genes within the cell. Specific genomic investigation of two Enterobactericeae isolates and the proteomic study of a third, underscored the potential of massive omic approaches to study antibiotic resistance as a global process. One of the key findings released from these studies is that antibiotic resistance is not only linked to virulence and pathogenicity, but can also be connected to core bacterial metabolic processes. The results obtained throughout this thesis extend our knowledge on the distribution of mobile antibiotic resistance genes in animals, environment and, ultimately, in the food chain. If the gathered results increased our concerns towards the current distribution of antibiotic resistant bacteria, they can also be an encouragement to address this problem at a global scale.
    2016-05Doctoral thesis Restricted access Show more