Prudent use of antibacterial agents: are we entering in an era of infections with no effective antibacterial agents? What can we do?

Abstract

In the last decade we have witnessed a dramatic increase in the number of bacterial pathogens presenting multi-resistance to antibacterial agents. In fact, several organizations such as the European Centre for Diseases Control and the World Health Organization are considering infections caused by multidrug resistant bacteria as an emergent disease. When we talk about multidrug resistant bacteria we should take into consideration not only the emergence but also the spread of multidrug resistant bacteria and the spread of genetic elements carrying resistant determinants. Emergence of microorganisms resistant to antibacterial agents, either by mutations or by the acquisition of new mobile genetic elements, may take place irrespective of the presence of antibacterial agents. It is the exposure to these drugs that provides an advantage to cells with the newly gained phenotype. Therefore, abuse in the use of antibacterials in several settings is the motivating force in the increase of antibacterial resistance. The first of these settings is the use of antibacterial agents in animals, as prophylaxis or treatment of infections. The multidrug resistant bacteria selected in animals can arrive in humans through direct contact or through the food chain. However, it is also possible that our normal gut microbiota have gained antibiotic resistance from antibiotic-exposed food animals. It is important to highlight that pets have recently been reported as reservoirs of multidrug resistant bacteria such as ESBLproducing Escherichia coli. Finally, the use of antibacterial agents in aquaculture has been associated with increased antibiotic resistance. The use of antibiotics in animals can also be a source of these compounds in the environment. Overall, it has been calculated that antibacterial agents are added to the environment at a rate of over a million pounds per week. Antibacterial agents have several routes of entry into the environment. Studies have shown that introduction by these routes has changed the antibiotic susceptibility of the bacteria in these environments. First of all, the antibacterial agents that we take in are not all