Yersinia enterocolitica in slaughter pig tonsils: Enumeration and detection by enrichment versus direct plating culture

Inge Van Damme, Ihab Habib, Lieven De Zutter

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)

Abstract

Tonsil samples from 139 slaughter pigs were examined for the presence of pathogenic Yersinia enterocolitica by enrichment procedures based on the standard method ISO 10273:2003. In addition, samples were tested by direct plating method to evaluate its efficiency compared to the enrichment culture methods and to quantify the level of contamination in porcine tonsils. In total, 52 samples (37.4%) were positive for pathogenic Y. enterocolitica, all belonging to bioserotype 4/O:3. Fifty out of the 52 positive samples (96.2%) were detected by direct plating. Enumeration showed an average concentration of 4.5 log10 CFU g-1 and 4.4 log10 CFU g-1 tonsil on Salmonella-Shigella-desoxycholate-calcium chloride (SSDC) and cefsulodin-irgasan-novobiocin (CIN) agar plates, respectively. The enrichment procedures recommended by the ISO 10273:2003 method were not optimal for the isolation of pathogenic Y. enterocolitica from pig tonsils: two days enrichment in irgasan-ticarcillin-potassium chlorate (ITC) broth resulted in an isolation rate of 84.6%, while 5 days enrichment in peptone-sorbitol-bile (PSB) broth recovered only 59.6% of positive samples. Reducing the enrichment time in PSB from 5 to 2 days resulted in a significantly higher recovery rate (94.2%) and might serve as an appropriate enrichment protocol for the isolation of pathogenic Y. enterocolitica from pig tonsils. Compared to enrichment culture methods, results based on direct plating can be obtained in a shorter time course and provide quantitative data that might be needed for further risk assessment studies.

Original languageEnglish
Pages (from-to)158-161
Number of pages4
JournalFood Microbiology
Volume27
Issue number1
DOIs
Publication statusPublished - Feb 2010
Externally publishedYes

Keywords

  • Enrichment
  • Enumeration
  • Isolation
  • Pathogenic Yersinia enterocolitica
  • Pig
  • Tonsil

ASJC Scopus subject areas

  • Food Science
  • Microbiology

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