Abstract
Anthropic activity in Antarctica has been increasing considerably in recent years, which could have an important impact on the local microbiota affecting multiple features, including the bacterial resistome. As such, our study focused on determining the antibiotic-resistance patterns and antibiotic-resistance genes of bacteria recovered from freshwater samples collected in areas of Antarctica under different degrees of human influence. Aerobic heterotrophic bacteria were subjected to antibiotic susceptibility testing and PCR. The isolates collected from regions of high human intervention were resistant to several antibiotic groups, and were mainly associated with the presence of genes encoding aminoglycosides-modifying enzymes (AMEs) and extended-spectrum β-lactamases (ESBLs). Moreover, these isolates were resistant to synthetic and semi-synthetic drugs, in contrast with those recovered from zones with low human intervention, which resulted highly susceptible to antibiotics. On the other hand, we observed that zone A, under human influence, presented a higher richness and diversity of antibiotic-resistance genes (ARGs) in comparison with zones B and C, which have low human activity. Our results suggest that human activity has an impact on the local microbiota, in which strains recovered from zones under anthropic influence were considerably more resistant than those collected from remote regions.
Highlights
The rise of antibiotic-resistant bacteria occurred few years after the beginning of the antibiotic era[1], and is mediated either by mutations or by the horizontal transfer of foreign resistance genes among environmental and/or nosocomial bacteria
In the case of heterotrophic bacteria with decreased susceptibility to antibiotics, we observed significant differences (p < 0.05) between the counts from zones B and C in the plates supplemented with nalidixic acid (NAL), STR, KAN and CTX
The highest counts of bacteria with decreased susceptibility to antibiotics were from zone B in agreement with the antibiotic susceptibility patterns, as a higher number of resistant isolates was present in this region
Summary
The rise of antibiotic-resistant bacteria occurred few years after the beginning of the antibiotic era[1], and is mediated either by mutations or by the horizontal transfer of foreign resistance genes among environmental and/or nosocomial bacteria. In this sense, it is well known that the environment can act as a reservoir of antibiotic-resistance genes (ARGs)[2,3,4]. The aim of this study was to evaluate the antibiotic-resistance features of bacterial isolates recovered from freshwater samples collected in regions under differential anthropic influence in Fildes Peninsula, King George Island, Antarctica
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