Resumen de Molecular epidemiology and mechanisms of cephalosporin resistance in escherichia coli of different origins; broilers, flies and white storks
Bacteria resistant to antimicrobials, and specifically to extended-spectrum beta-lactamases (ESBLs), have become of increasing concern. Its prevalance has increased fast worldwide due to a pandemic dissemination of plasmids and the introduction of ESBL resistance genes into successful clones (Coque, Baquero et al. 2008, Brolund 2014). According to the World Health Organization (WHO) the most critical antimicrobials in human and animal health are third-generation cephalosporins, fluoroquinolones, macrolides and amynoglycosides (Collignon, Powers et al. 2009, Collignon, Conly et al. 2016). Therefore, this thesis has focused in resistance to cephalosporins and particularly to ESBLs and AmpC type of resistance.
Due to the overuse of antimicrobials in humans and veterinary medicine, the emergence of multi-drug resistance has increased in the last decades. Most of the research has focused on the epidemiology of antibiotic resistance in human and veterinary medicine; however, in the last years it has been an increasing attention on how multiresistant bacteria circulates in natural environments and how these niches can act as reservoirs of resistant traits (Allen, Donato et al. 2010). Once the resistant bacteria are present in the environment, it can easily get in contact with humans.
Through the studies compiled in this thesis, we have investigated the occurrence and mechanisms of dissemination of cephalosporin resistance (CR) Escherichia coli from different ecological niches; broilers as an example of food-producing animals, houseflies (Musca domestica) as mechanical vectors and reservoir of resistance genes contributing to the spread of resistance in the farm environment; and finally white storks (Ciconia ciconia) as an example of long-distance vectors and sentinels of human pressure. With this approach, we intend to understand the transmissibility of these resistances among different niches; and identify clones, resistance genes and plasmids involved.
