Antibiotic resistance in bacteria from seawater surrounding antarctic stations

Abstract

Antimicrobial resistant bacteria are widespread in aquatic environments. The aim of the present study was to obtain information on the occurrence of bacteria with antimicrobial resistance in seawater surrounding Antarctic stations.

Escherichia coli strains were isolated from seawater. The samples were collected from sites distributed around the sewage outfalls of seven Antarctic stations. Antibiotic susceptibility patterns were determined with the disk diffusion method using different groups of antibiotics: penicillins, carbapenems, aminoglycosides, quinolones, tetracycline, phenicols and trimethoprim. Escherichia coli ATCC 25922 was used as the control for the susceptibility tests.

A total of 216 samples were analysed. Escherichia coli were detected in 58 % of the samples. The highestbacterial counts were found in seawater surrounding the sewage outfalls. However, the bacterial counts decreased rapidly with increasing distance from the outfall. Seventy strains isolated were studied to determine antibiotic susceptibility. The strains studied showed resistant to 16 out of the 17 antibiotics tested. Thirty-six strains were susceptible to all the antibiotics tested Thirty-four were resistant to at least one antibiotic, 12 were multidrug resistant and 20 showed resistant to Ampicillin. Finally, the presence of extended-spectrum beta-lactamases (ESBLs) was determined in two strains studied.

The presence of bacteria with antimicrobial resistance in the Antarctic environment is indicative of how widespread the global antibiotic resistance situation has become.