Use of a single procedure for selective enrichment, isolation, and identification of plasmid-bearing virulent Yersinia enterocolitica of various serotypes from pork samples.
Many selective enrichment methods for the isolation of Yersinia enterocolitica from foods have been described. However, no single isolation procedure has been described for the recovery and identification of various plasmid-bearing serotypes. A single improved procedure for selective enrichment, isolation, identification, and maintenance of plasmid-bearing virulent serotypes of Y. enterocolitica from pork samples was developed. Enrichment at 12 degrees C in Trypticase soy broth containing yeast extract, bile salts, and Irgasan was found to be an efficient medium for the recovery of plasmid-bearing virulent strains of Y. enterocolitica representing O:3; O:8; O:TACOMA; O:5, O:27; and O:13 serotypes. MacConkey agar proved to be a reliable medium for the isolation of presumptive colonies, which were subsequently confirmed as plasmid-bearing virulent strains by Congo red binding and low calcium response. Further confirmation by multiplex PCR employed primers directed at the chromosomal ail and plasmid-borne virF genes, which are present only in pathogenic strains. The method was applied to pig slaughterhouse samples and was effective in isolating plasmid-bearing virulent strains of Y. enterocolitica from naturally contaminated porcine tongues. Strains isolated from ground pork and tongue expressed plasmid-associated phenotypes and mouse pathogenicity.
Bhaduri
S
S
Microbial Food Safety Research Unit, U.S. Department of Agriculture, Wyndmoor, Pennsylvania 19038, USA. sbhaduri@arserrc.gov
Cottrell
B
B
Pickard
A R
AR
D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D001681:Biological Assay; D002118:Calcium / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry / Q000378:metabolism; D008460:Meat / Q000382:microbiology*; D051379:Mice; D019081:O Antigens / Q000276:immunology; D010957:Plasmids / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D013552:Swine; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors; D015008:Yersinia enterocolitica / Q000235:genetics* / Q000254:growth & development* / Q000276:immunology / Q000472:pathogenicity
C069712:Ail protein, Yersinia enterocolitica; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D003470:Culture Media; D019081:O Antigens; D037521:Virulence Factors; D002118:Calcium