Paulo Martins da Costa (ICBAS and CIIMAR /UPorto) | October 17, 2014 - 14h30 | CIBIO’s Auditorium, Campus de Vairão

 

In the last decades, antimicrobial use in both human and animal populations was the major driver of antimicrobial resistance, providing the selective pressure necessary to modulate the emergence, transfer, spread, and stability of genes responsible for antimicrobial resistance in both human and veterinary pathogens. This problem is often conceptualized in terms of resistance to specific antimicrobials in pathogens of clinical importance, rather than ecologically in terms of reservoirs of resistance genes that may flow across the microbial ecosystem. Indeed, the same genetic determinants responsible for phenotypes of resistance have been identified among bacteria isolated from humans, animals (food producing, companion, wild) or the environment. Furthermore, the general environment (water, soil, wild life) has been gradually recognised as the most important location of emergence of resistance due to the confluence of a polymicrobial community (enormous number of bacteria and species) with the presence of subinhibitory concentrations of antimicrobials. In fact, the release of antibiotics in the environment (e.g. effluents from urban areas and animal production units) artificially creates concentration gradients that trigger different cellular responses and genes exchange, which may include an altered antibiotic resistance/tolerance profile. Thus, the larger the distribution of antibiotics, the greater the chance that in some place a large population of bacteria will be in contact with the correct selecting (non-lethal) concentration of the antibiotic.
On the other hand, Nature is a rich full and endless source of bioactive compounds that must be explored to search for new compounds with antimicrobial activity as well as compounds with the ability to revert the resistance mechanisms acquired by bacteria when combined with antibiotics to which bacteria have already developed resistance.

 

Paulo Martins da Costa is auxiliar professor at Instituto de Ciências Biomédicas de Abel Salazar (ICBAS) da Universidade do Porto since 2006, teaching in the areas of food technology and food safety. He graduated in Veterinary Medicine from the Faculdade de Medicina Veterinária/UTL) and obtained Ph.D. in Biomedical Sciences (Microbiology) in ICBAS/UPorto; thesis on the assessment of the selective pressure in enterococci and Escherichia coli caused by the preventive use of antimicrobial agents in intensive reared broilers. Results showed that changes observed over time were influenced drug-resistant bacteria previously present in the farm environment and those present in feedstuffs. To study the possibilities of transfer of resistant phenotypes between biomes, several studies have been performed to determine the prevalence of antimicrobial resistance, to characterize the phylogenetic background of strains and to identify resistance determinants among E. coli, enterococci and Staphylococcus aureus isolated from (i) wastewater treatment plants, rivers and city lakes and fountains, (ii) food producing animals (swine, bovine and rabbits), bivalves, gulls, birds of prey, wolves, dogs, cats and humans, and (iii) transport services (urban buses and trains) and clinical veterinary environment.

More recently, has been involved in two research projects (CIIMAR/UPorto) aiming to tackle the potentiality of compounds obtained from natural sources to directly or indirectly (due to an synergic interaction with current antibiotics) fight the actual problem of antimicrobial resistance.

 

[Group Leader: Fernando Tavares, Microbial Diversity and Evolution]

 

Image credits: Paulo Martins da Costa