DETECTION OF ENTEROPATHOGENIC ESCHERICHIA -COLI IN SPREADABLE DRY SAUSAGE

Fresh Mettwurst (a dry sausage eaten relatively fresh) is normally mad e with the aid of starter cultures. 2.1% and 3.0% lactate was added to part of a batch of Mettwurst and the sausages were inoculated with di fferent levels of various serovars of enterohaemorrhagic E. coli (EHEC ). These were E. coli O157:H7, O157:H-, O111:H- and O26:H11 from the c ollection of the Robert Koch Institute in Berlin. The sausages were ri pened for 2 days (at about 20 degrees C), then sored for 2 and 4 weeks at 4 degrees C and then examined. To check the ripeness and state of hygiene of the fresh Mettwurst the numbers of lactobacilli, micrococci , total bacterial count, Enterobacteriaceae and pseudomonads were dete rmined. The pH and a(w) and also the D-lactic acid content were measur ed and colour and spreadability were also assessed. The indicator subs trates Fluorocult (R) E. coli O157:H7-agar, MacConkey sorbite agar and the recently developed Enterohaemolysin agar with Vancomycin were use d to detect and confirm EHEC. Further methods of enrichment or confirm ation of EHEC were immuno-magnetic separation (IMS, up to now only for E. coli O157), slide agglutination and toxin determination (for Shiga -like toxins). In spite of dry sausage ripening being typical it was f ound that the EHEC survived ripening and storage but did not increase in numbers. The result was the same for all Mettwurst, irrespective of the EHEC serovars with which the sausage was inoculated and irrespect ive of whether lactate was added or not. Even the level of organisms i noculated (between 1000 org./g and 2 org./g) had no decisive influence on the result. EHEC-contaminated fresh Mettwurst can therefore be a p otential risk of infection to the consumer. Manufacturers must therefo re strictly observe the hygiene regulations in relation to GMP and HAC CP.