[Injudicious and excessive use of antibiotics: public health and salmon aquaculture in Chile].

Salmon aquaculture was one of the major growing and exporting industries in Chile. Its development was accompanied by an increasing and excessive use of large amounts of antimicrobials, such as quinolones, tetracyclines and florfenicol. The examination of the sanitary conditions in the industry as part of a more general investigation into the uncontrolled and extensive dissemination of the ISA virus epizootic in 2008, found numerous and wide-ranging shortcomings and limitations in management of preventive fish health. There was a growing industrial use of large amounts of antimicrobials as an attempt at prophylaxis of bacterial infections resulting from widespread unsanitary and unhealthy fish rearing conditions. As might be expected, these attempts were unsuccessful and this heavy antimicrobial use failed to prevent viral and parasitic epizootics. Comparative analysis of the amounts of antimicrobials, especially quinolones, consumed in salmon aquaculture and in human medicine in Chile robustly suggests that the most important selective pressure for antibiotic resistant bacteria in the country will be excessive antibiotic use in this industry. This excessive use will facilitate selection of resistant bacteria and resistance genes in water environments. The commonality of antibiotic resistance genes and the mobilome between environmental aquatic bacteria, fish pathogens and pathogens of terrestrial animals and humans suggests that horizontal gene transfer occurs between the resistome of these apparently independent and isolated bacterial populations. Thus, excessive antibiotic use in the marine environment in aquaculture is not innocuous and can potentially negatively affect therapy of bacterial infections of humans and terrestrial animals.