RESUMO
The prevalence of Yersinia enterocolitica on chicken eggshell surfaces in San Luis, Argentina, was investigated. The pathogenic potential of recovered isolates was assessed by means of phenotypic virulence tests and the presence of the 72-kb pYV plasmid. Antimicrobial susceptibility was determined by the agar diffusion method. DNA digested with XbaI was analyzed by pulsed-field gel electrophoresis (PFGE), and relationships between genomic DNA profiles were established. Eight Y. enterocolitica B2 O:9 strains were recovered after enrichment, for a prevalence of 2.27%. All strains harbored the virulence pYV plasmid, bound Congo red, grew in a low-calcium medium, and autoagglutinated at 37 degrees C. They lacked pyrazinamidase activity and did not hydrolyze esculin. These Y. enterocolitica strains were susceptible to amikacin, ciprofloxacin, chloramphenicol, and trimethoprim-sulfamethoxazole and were resistant to rifampin. According to the genomic DNA patterns obtained by PFGE, the isolates clustered into two groups, I and II. The highest similarity coefficient observed between Y. enterocolitica strains was 0.947. Microbiological controls on production stages of eggs and good culinary practices are necessary to reduce the risk of Y. enterocolitica infection for consumers.
Assuntos
Casca de Ovo/microbiologia , Microbiologia de Alimentos , Genes Bacterianos/genética , Yersinia enterocolitica , Animais , Antibacterianos/farmacologia , Argentina , Proteínas da Membrana Bacteriana Externa , Galinhas , Contagem de Colônia Microbiana , Impressões Digitais de DNA , Genótipo , Testes de Sensibilidade Microbiana , Fenótipo , Virulência , Yersinia enterocolitica/efeitos dos fármacos , Yersinia enterocolitica/isolamento & purificação , Yersinia enterocolitica/patogenicidadeRESUMO
A search of Yersinia enterocolitica in foods of animal origin has been carried out. Isolates were obtained from 450 samples of cold foods: 100 samples of cooked ham, 150 samples of salami, 100 samples of porcine cheese (artisan cold foods), and 100 samples of mortadella. Enrichments were performed in 0.067 M phosphate buffered saline solutions, pH 7. 6, containing 1% sorbitol and 0.15% biliary salts. The samples were postenriched in 0.5% KOH. Subcultures were done in Salmonella-Shigella agar and MacConkey agar. Isolates were identified through biochemical, serological, and phagotyping methods. The following biovars (B), serovars (O), and phagovars (Lis) were isolated from cooked ham B2 0:9 Lis X3 (1%), from salami B1 0:5 Lis Xz and B2 0:9 Lis X3 (1.33%), from porcine cheese B2 0:9 Lis X3 (2%), and from mortadella (0%). Virulence tests (calcium dependent growth at 37°C and autoagglutination activity at 37°C) were always negative. Serovar B2 0:9 Lis X3 associated with human disease was isolated. It is concluded from the results of this study that Y. enterocolitica isolates from cold foods lack of pathogenic importance.
RESUMO
Twenty-six strains of Yersinia enterocolitica isolated from fresh sausages, bovine tongues, and porcine ceca and tongues were evaluated for the production of heat-stable enterotoxin (ST, infant mouse test) in trypticase soy broth (TSB) and casamino acids broth (CAB). The gut weight/body weight ratios obtained with the two media were similar. Sixteen strains produced ST in both media; nine strains did not. Strain 23 produced ST in CAB but not in TSB.