Antibacterial resistant bacteria in surficial sediments near salmon net-cage farms in Puget Sound, Washington
- 1 March 1997
- journal article
- Published by Elsevier BV in Aquaculture
- Vol. 149 (3-4), 263-283
- https://doi.org/10.1016/s0044-8486(96)01455-x
Abstract
Antibacterials are used in medicated fish feed at fish farms located in Puget Sound, Washington. These compounds include oxytetracycline (OTC), amoxycillin, and Romet ® 30 (a drug composed of sulfadimethioxine and ormetoprim). In this study we collected surficial sediment samples at three different commercial salmon net-cage farms during the summer and early fall of 1992. The three different farms varied in their use of antibacterials. Before beginning our field investigation we developed a modification of Mueller Hinton Agar to enumerate antibacterial-resistant bacteria. A synthetic seawater was added at 70% concentration to Mueller Hinton Agar. Because the divalent cations present in seawater chelate OTC, the concentration of this antibacterial was increased in the seawater medium relative to concentrations typically used in clinical microbiology laboratories. We enumerated the total number of cultivable bacteria, and bacteria resistant to oxytetracycline, amoxycillin, or Romet ® 30 by plating aliquots of sediment samples onto the marine Mueller Hinton Agar. The highest numbers of bacteria (10 6 to 10 8 colony forming units g −1 ) were generally found nearest the net-cages with densities declining about an order-of-magnitude further away from the cages. Farm A, which used the greatest amount of antibacterials of the three farms, had the highest percentages of antibacterial-resistant bacteria in the sediments. At this Farm resistance to Romet ® 30 and OTC tended to parallel each other, suggesting either a common resistance mechanism or linkage of the genes responsible for the resistances. Farm C used the least amount of antibacterials and this was reflected in that this farm also had the lowest percentage of sedimentary bacteria that were resistant to the antibacterials. Although the total number of bacteria at Farm C was in a similar range as found at Farms A and B, the percentages of antibacterial resistant bacteria were 5% or less for most of the samples. Our results suggest that a background of less than 5% of the cultivable bacteria in marine sediments is resistant to OTC, Romet ® 30, or amoxycillin.Keywords
This publication has 29 references indexed in Scilit:
- Antibacterial residues in marine sediments and invertebrates following chemotherapy in aquacultureAquaculture, 1996
- Concentration and persistence of oxytetracycline in sediments under a marine salmon farmAquaculture, 1994
- Residues of oxolinic acid and oxytetracycline in fish and sediments from fish farmsAquaculture, 1991
- Cross resistance between oxytetracycline and oxolinic acid inAeromonas salmonicidaassociated with alterations in outer membrane proteinsFEMS Microbiology Letters, 1990
- Residues of oxytetracycline in wild fish and sediments from fish farmsAquaculture, 1990
- Genetic exchange in the environmentAntonie van Leeuwenhoek, 1989
- Prevention of Infectious Diseases in AquacultureJournal of Veterinary Medicine, Series B, 1989
- The effect of antimicrobial compounds on the gastrointestinal microflora of rainbow trout, Salmo gairdneri RichardsonJournal of Fish Biology, 1988
- The susceptibility of Aeromonas salmonicida strains isolated in cultured and wild salmonids to various chemotherapeutics.NIPPON SUISAN GAKKAISHI, 1983
- In Vitro and In Vivo Efficacy of a Potentiated Sulfonamide in Control of Furunculosis in SalmonidsJournal of the Fisheries Research Board of Canada, 1974