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Horizontal gene transfer of a ColV plasmid has resulted in a dominant avian clonal type of Salmonella enterica serovar Kentucky.

Johnson TJ, Thorsness JL, Anderson CP, Lynne AM, Foley SL, Han J, Fricke WF, McDermott PF, White DG, Khatri M, Stell AL, Flores C, Singer RS - PLoS ONE (2010)

Bottom Line: Of the serovars examined, the ColV plasmid was found only among isolates belonging to the serovars Kentucky (72.9%), Typhimurium (15.0%) and Heidelberg (1.7%).Kentucky significantly increased its ability to colonize the chicken cecum and cause extraintestinal disease.Thus, the potential for horizontal gene transfer of virulence and fitness factors to Salmonella from other enteric bacteria exists in poultry, representing a potential human health hazard.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary and Biomedical Sciences, University of Minnesota, St Paul, Minnesota, United States of America. joh04207@umn.edu

ABSTRACT
Salmonella enterica continues to be a significant cause of foodborne gastrointestinal illness in humans. A wide variety of Salmonella serovars have been isolated from production birds and from retail poultry meat. Recently, though, S. enterica subsp. enterica serovar Kentucky has emerged as one of the prominent Salmonella serovars isolated from broiler chickens. Recent work suggests that its emergence apparently coincides with its acquisition of a ColV virulence plasmid. In the present study, we examined 902 Salmonella isolates belonging to 59 different serovars for the presence of this plasmid. Of the serovars examined, the ColV plasmid was found only among isolates belonging to the serovars Kentucky (72.9%), Typhimurium (15.0%) and Heidelberg (1.7%). We demonstrated that a single PFGE clonal type of S. Kentucky harbors this plasmid, and acquisition of this plasmid by S. Kentucky significantly increased its ability to colonize the chicken cecum and cause extraintestinal disease. Comparison of the completed sequences of three ColV plasmids from S. Kentucky isolated from different geographical locales, timepoints and sources revealed a nearly identical genetic structure with few single nucleotide changes or insertions/deletions. Overall, it appears that the ColV plasmid was recently acquired by a single clonal type S. Kentucky and confers to its host enhanced colonization and fitness capabilities. Thus, the potential for horizontal gene transfer of virulence and fitness factors to Salmonella from other enteric bacteria exists in poultry, representing a potential human health hazard.

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Related in: MedlinePlus

Growth curves of selected isolates in (A) LB broth, (B) human serum, (C) chicken serum, and (D) LB broth +200 uM 2,2′-dipyridyl.Strains with “p” refer to the transconjugant of a strain containing pCVM29188_146, while strains with “c” refer to a wild type strain cured of its ColV plasmid.
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pone-0015524-g002: Growth curves of selected isolates in (A) LB broth, (B) human serum, (C) chicken serum, and (D) LB broth +200 uM 2,2′-dipyridyl.Strains with “p” refer to the transconjugant of a strain containing pCVM29188_146, while strains with “c” refer to a wild type strain cured of its ColV plasmid.

Mentions: A collection of ColV plasmid-containing and plasmid-lacking Salmonella isolates (Table 3) was used to test their abilities to grow in LB broth, LB broth supplemented with 200 uM 2,2′-dipyridyl (low iron media), 50% human serum in LB broth, and 100% chicken serum over an 18-hour period (Fig. 2). In LB broth, no differences were observed between plasmid-containing and plasmid-lacking strains, but S. Newport strain SL317 grew better than other strains over the 18-hr time period. In 50% human serum, S. Newport SL317p fared slightly better than S. Newport SL317 while no other differences were observed between plasmid-containing and plasmid-lacking strains. S. Newport SL317 and S. Kentucky CVM35942 grew the best in human serum, while S. Kentucky strains CVM29188 and SSAP03002A performed poorly. In 100% chicken serum, no differences were observed between plasmid-containing and plasmid-lacking strains. However, S. Kentucky strains CVM35942, CS0010-A, and SSAP03002A performed better than other strains in this medium. In low iron media, the isolates generally grew poorly, except that S. Newport SL317p grew better than its plasmid-lacking counterpart SL317.


Horizontal gene transfer of a ColV plasmid has resulted in a dominant avian clonal type of Salmonella enterica serovar Kentucky.

Johnson TJ, Thorsness JL, Anderson CP, Lynne AM, Foley SL, Han J, Fricke WF, McDermott PF, White DG, Khatri M, Stell AL, Flores C, Singer RS - PLoS ONE (2010)

Growth curves of selected isolates in (A) LB broth, (B) human serum, (C) chicken serum, and (D) LB broth +200 uM 2,2′-dipyridyl.Strains with “p” refer to the transconjugant of a strain containing pCVM29188_146, while strains with “c” refer to a wild type strain cured of its ColV plasmid.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3008734&req=5

pone-0015524-g002: Growth curves of selected isolates in (A) LB broth, (B) human serum, (C) chicken serum, and (D) LB broth +200 uM 2,2′-dipyridyl.Strains with “p” refer to the transconjugant of a strain containing pCVM29188_146, while strains with “c” refer to a wild type strain cured of its ColV plasmid.
Mentions: A collection of ColV plasmid-containing and plasmid-lacking Salmonella isolates (Table 3) was used to test their abilities to grow in LB broth, LB broth supplemented with 200 uM 2,2′-dipyridyl (low iron media), 50% human serum in LB broth, and 100% chicken serum over an 18-hour period (Fig. 2). In LB broth, no differences were observed between plasmid-containing and plasmid-lacking strains, but S. Newport strain SL317 grew better than other strains over the 18-hr time period. In 50% human serum, S. Newport SL317p fared slightly better than S. Newport SL317 while no other differences were observed between plasmid-containing and plasmid-lacking strains. S. Newport SL317 and S. Kentucky CVM35942 grew the best in human serum, while S. Kentucky strains CVM29188 and SSAP03002A performed poorly. In 100% chicken serum, no differences were observed between plasmid-containing and plasmid-lacking strains. However, S. Kentucky strains CVM35942, CS0010-A, and SSAP03002A performed better than other strains in this medium. In low iron media, the isolates generally grew poorly, except that S. Newport SL317p grew better than its plasmid-lacking counterpart SL317.

Bottom Line: Of the serovars examined, the ColV plasmid was found only among isolates belonging to the serovars Kentucky (72.9%), Typhimurium (15.0%) and Heidelberg (1.7%).Kentucky significantly increased its ability to colonize the chicken cecum and cause extraintestinal disease.Thus, the potential for horizontal gene transfer of virulence and fitness factors to Salmonella from other enteric bacteria exists in poultry, representing a potential human health hazard.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary and Biomedical Sciences, University of Minnesota, St Paul, Minnesota, United States of America. joh04207@umn.edu

ABSTRACT
Salmonella enterica continues to be a significant cause of foodborne gastrointestinal illness in humans. A wide variety of Salmonella serovars have been isolated from production birds and from retail poultry meat. Recently, though, S. enterica subsp. enterica serovar Kentucky has emerged as one of the prominent Salmonella serovars isolated from broiler chickens. Recent work suggests that its emergence apparently coincides with its acquisition of a ColV virulence plasmid. In the present study, we examined 902 Salmonella isolates belonging to 59 different serovars for the presence of this plasmid. Of the serovars examined, the ColV plasmid was found only among isolates belonging to the serovars Kentucky (72.9%), Typhimurium (15.0%) and Heidelberg (1.7%). We demonstrated that a single PFGE clonal type of S. Kentucky harbors this plasmid, and acquisition of this plasmid by S. Kentucky significantly increased its ability to colonize the chicken cecum and cause extraintestinal disease. Comparison of the completed sequences of three ColV plasmids from S. Kentucky isolated from different geographical locales, timepoints and sources revealed a nearly identical genetic structure with few single nucleotide changes or insertions/deletions. Overall, it appears that the ColV plasmid was recently acquired by a single clonal type S. Kentucky and confers to its host enhanced colonization and fitness capabilities. Thus, the potential for horizontal gene transfer of virulence and fitness factors to Salmonella from other enteric bacteria exists in poultry, representing a potential human health hazard.

Show MeSH
Related in: MedlinePlus