Ein Beitrag zum Vorkommen von Yersinia enterocolitica in Hackfleisch und Fleischerzeugnissen vom Schwein im Hinblick auf die eingesetzten Kultur- und Isolierungsverfahren

Occurence of pathogenic Y. enterocolitica 4/O:3 in pork in southern
Germany The prevalence of pathogenic Yersinia enterocolitica in
pork products in Southern Germany was studied because no data is
available of distribution of this pathogen at retail level in
Germany. A total of 300 meat products containing pork from
different plants were collected between May and August year 2000.
These samples consist of 215 raw and 85 heat-treated products. The
samples were studied with different culture methods: direct
plating, overnight enrichment in TSB combined with alkali
treatment, selective enrichment in MRB and ITC, and cold enrichment
in TSB followed by alkali treatment. Y. enterocolitica was isolated
from selective CIN agar plates. Urea-positive colonies were
identified using API 20E. Y. enterocolitica isolates were bio- and
serotyped, and the pathogenicity was confirmed with Congo red
binding and Calcium dependence on CRMOX agar plates. Pathogenic Y.
enterocolitica was recovered from raw meat products but not from
heat-treated products. The isolation rate of Y. enterocolitica
4/O:3 in minced meat was 9.0%. This type was also found two times
(7.4%) from raw pork. All pathogenic Y. enterocolitica isolates
were belonging to bioserotype 4/O:3. Selective enrichment in ITC
was shown to be the most productive method for raw meat products.
No pathogenic Y. enterocolitica isolates could be recovered after
non- selective enrichment even when combined with alkali treatment.
These results show that raw pork can be one source of Y.
enterocolitica 4/O:3 infections among humans in Southern Germany.
This study also demonstrates that no pathogenic Y. enterocolitica
can be found without selective enrichment.