Impacto de atividades antrópicas em uma bacia hidrográfica: epidemiologia da resistência bacteriana às drogas antimicrobianas

Abstract

Water is the main resource for maintaining life. Microbiological quality is one of the most important characteristics of consumption water, enabling microbial communities to function as indicators of human interference in these ecosystems. In addition, rivers and streams may be important pathways for the spread of antimicrobial resistant bacteria, and searching for genetic markers of resistance makes it possible to know their clinical resistome. Metagenomic studies, through molecular techniques such as sequencing and PCR, provide in-depth knowledge of the microbial community and its antimicrobial resistance profile. It is believed that the anthropic activities, both those related to urbanization and those of agriculture and family farms and small properties, influence the microbial epidemiological chain in watersheds, which can act as ways of disseminating microorganisms resistant to antimicrobial drugs and potentially pathogens, with impacts on human, animal and environmental health. This study aims to evaluate the presence of resistance markers to antimicrobial drugs in water samples of a watershed. In this study, 12 water samples were collected at different points of the Rio das Ostras river in two distinct periods. In these samples, physical-chemical analyzes were performed (pH, Dissolved Oxygen, conductivity and salinity). DNA was extracted from the samples and genetic resistance markers were searched for different classes of antimicrobials using PCR. The samples obtained from the river already in urbanized area presented values of conductivity and salinity higher and some points with pH expressively smaller than the other points of sampling during the course of the river. On the other hand, dissolved oxygen values were higher in the rural area and at high tide point in the estuary of the river in question. Twenty-six genetic resistance markers were identified among the samples, and they were most frequently found at collection points located in the urban area. Among the resistance genes studied, sul1, ereB and tet (Q) were the most frequent, which were detected in about 80% of the samples. Principal component analysis (PCA) showed that the samples were grouped according to their sampling location in the course of the river based on the occurrence profile of genetic markers of antimicrobial resistance. It can be concluded that the resistance markers researched may represent water contamination by both human and animal resistant bacteria and it is suggested that the anthropogenic activities carried out around the basin have a great influence on the frequency of resistance markers found, as well as the class of antimicrobials they represent.