Antimicrobials used in salmon aquaculture pass into the marine environment. This could have negative impacts on marine environmental biodiversity, and on terrestrial animal and human health as a result of selection for bacteria containing antimicrobial resistance genes. We therefore measured the numbers of culturable bacteria and antimicrobial-resistant bacteria in marine sediments in the Calbuco Archipelago, Chile, over 12-month period at a salmon aquaculture site approximately 20 m from a salmon farm and at a control site 8 km distant without observable aquaculture activities. Three antimicrobials extensively used in Chilean salmon aquaculture (oxytetracycline, oxolinic acid, and florfenicol) were studied. Although none of these antimicrobials was detected in sediments from either site, traces of flumequine, a fluoroquinolone antimicrobial also widely used in Chile, were present in sediments from both sites during this period. There were significant increases in bacterial numbers and antimicrobial-resistant fractions to oxytetracycline, oxolinic acid, and florfenicol in sediments from the aquaculture site compared to those from the control site. Interestingly, there were similar numbers of presumably plasmid-mediated resistance genes for oxytetracycline, oxolinic acid and florfenicol in unselected marine bacteria isolated from both aquaculture and control sites. These preliminary findings in one location may suggest that the current use of large amounts of antimicrobials in Chilean aquaculture has the potential to select for antimicrobial-resistant bacteria in marine sediments.

Summary: Antimicrobial resistance ( AR ) detected by disc diffusion and antimicrobial resistance genes detected by DNA hybridization and polymerase chain reaction with amplicon sequencing were studied in 124 marine bacterial isolates from a C hilean salmon aquaculture site and 76 from a site without aquaculture 8 km distant. Resistance to one or more antimicrobials was present in 81% of the isolates regardless of site. Resistance to tetracycline was most commonly encoded by tetA and tetG ; to trimethoprim, by dfrA1, dfrA5 and dfrA12 ; to sulfamethizole, by sul1 and sul2 ; to amoxicillin, by bla _TEM ; and to streptomycin, by strA‐strB . Integron integrase intl1 was detected in 14 sul1 ‐positive isolates, associated with aad9 gene cassettes in two from the aquaculture site. intl2 Integrase was only detected in three dfrA1 ‐positive isolates from the aquaculture site and was not associated with gene cassettes in any. Of nine isolates tested for conjugation, two from the aquaculture site transferred AR determinants to E scherichia coli . High levels of AR in marine sediments from aquaculture and non‐aquaculture sites suggest that dispersion of the large amounts of antimicrobials used in Chilean salmon aquaculture has created selective pressure in areas of the marine environment far removed from the initial site of use of these agents.

We examined sections of synovial membranes from 14 patients with rheumatoid arthritis (RA), 7 with other rheumatic diseases, and 10 with no apparent joint disease. Patients with RA and other rheumatic diseases had significantly more synovial mast cells/vessel than patients with no joint disease (0.49 and 0.20, respectively, versus 0.03). They also had significantly more total mast cells/10 fields than patients with no joint disease (9.9 and 5.0, respectively, versus 0.4). Within the rheumatoid group, patients with active disease had more total mast cells/10 fields than patients clinically considered to have end‐stage disease (P < 0.05). Synovial basophils were not identified in any patient. Synovial vascularity was similar for all groups (2.3 vessels/field). The role of the synovial mast cell in RA and other rheumatic diseases remains to be determined.