The prevalence of plasmids in Danish bovine and human isolates of Salmonella dublin

Abstract

Nine different plasmid profiles were demonstrated among 135 Danish isolates of Salmonella dublin, with 58% of the strains enclosed in the major profile group. Two strains did not carry any plasmids. The plasmid profiles of 129 strains (96%) were made up of one or more of only four plasmids of approximate sizes 98 kb, 80 kb, 4.0 kb, and 3.8 kb. There was no significant difference in the prevalence of different plasmid profile groups between isolates from cattle and man. The serovar‐specific and virulence‐associated 80 kb plasmid could be demonstrated in all plasmid carrying strains, but one strain carried this plasmid at a very low copy number. Five of 47 strains tested showed resistance to antibiotics (2 to sulphathiazole, 2 to streptomycin, and 1 to streptomycin and tetracycline). Only the combined streptomycin/tetracycline resistance was transferable by a 48 kb conjugative plasmid.

Epidemiology ofSalmonellaentericaSerotype Dublin Infections among Humans, United States, 1968–2013

“…Salmonella Dublin has been described as having a serotype-specific virulence-associated plasmid that is associated with invasive infection and remains stable through multiple generations of nonselective bacterial passage ( 12 ). Additional analyses, with use of whole-genome sequencing, particularly methods like those developed by Pacific Biosciences (Menlo Park, CA, USA) to use long-sequence reads and facilitate plasmid analysis, would enable investigation into the respective contributions of virulence factors and resistance mechanisms.…”

Plasmid profiling as an epidemiological marker within Aeromonas salmonicida

“…DNA samples (15 p1) were subjected to electrophoresis in 2 different gels: a 1 % agarose gel [Litex LSL agarose in Tris acetate EDTA buffer (TAE) (Maniatis et al 1982)j was used for the separation of small plasmids, and a 0.7 % agarose gel in TAE buffer was used for the separation of large plasmids. Small plasmids were separated at 30 V for 17 h; large plasmids were separated at 80 V for 3 h. Plasmids were visualised as previously described (Olsen et al 1990).…”

Characterization of isolates of Flavobacterium psychrophilum associated with coldwater disease or rainbow trout fry syndrome:phenotypic and genomic studies

“…Plasmids appeared after 2 to 3 h at 8 to 9 V cm-' using a mini-gel electrophoresis unit (gel size of 7 X 8.5 cm2). Visualization was made by staining with ethidium bromide (Sigma, 2 pg ml-' distilled water or 3 pg ml-' gel) followed by exposure to UV-light (254 nm) (Olsen et al 1990). Approximate molecular size of the plasmids was estimated from the migration patterns of supercoiled plasmids in 2 reference strains of Escherichia coli, V517 (Macrina et al 1978) and 39R861 (Threlfall et al 1986), using the regression equation recommended by Rochelle et al (1985).…”