Abstract

Antibiotic resistance is a problem of global concern and has been frequently associated with human activity. The study of antibiotic resistance in bacteria isolated from pristine environments like Antarctica contributes to the understanding of this fragile ecosystem. Escherichia coli strains, an important bacterial indicator of faecal pollution, were isolated and identified from samples taken from Fildes Peninsula‘s seawater (area with the highest human influence in Antarctica), Antarctic bird stool and inside one Fildes Peninsula‘s wastewater treatment plant. The strains were molecularly typed by PFGE to determine the genetic relations between them and submitted to antibiotic disk diffusion tests using the following antibiotic families: β-lactams, quinolones, aminoglycosides, tetracyclines, phenicols and trimethoprim-sulfonamide. The maximum E. coli count for seawater samples was 2400 cfu/100 mL. Genetic relatedness in-between groups, was only found within strains isolated from seawater and the wastewater treatment plant. Strains of both groups showed resistance to β-lactams, aminoglycosides, tetracycline and trimethoprim-sulfonamide. Whereas Antarctic bird stool isolated strains exhibited no antibiotic resistance at all. The antibiotic resistance profiles found in E. coli isolated from Fildes Peninsula seawater are a cause of concern, with the southern area having the highest in E. coli counts and most multidrug resistance. Comparing antibiotic resistance patterns of strains isolated from Antarctic bird stool, wastewater treatment plant and seawater, it is highly probable that these strains come from the wastewater treatment plant that discharge in the area. This work contributes to the field of antibiotic resistance of bacterial strains in Antarctica, and further research is needed in order to establish the horizontal gene transfer of resistance determinants to autochthonous Antarctic bacteria.