Distribution of mesophilic Aeromonas species in raw and ready-to-eat fish and meat products in Switzerland.

A total of 829 poultry, meat, shellfish and fish products commonly consumed in Switzerland were qualitatively and quantitatively examined for the presence of mesophilic Aeromonas spp. Overall, aeromonads occurred in 24.1% of the samples. Raw food products were frequently contaminated (e.g. 94.1% in minced meat), with colony counts up to 6.0 x 10(6)/g. Some ready-to-eat products had a relatively high percentage of positive samples as well, such as cooked ham in slices (38.2%), mortadella (12.9%), smoked cooked sausage (15.6%), hot and cold smoked fish (10.9-14.3%) and gravad salmon (10.5%). Colony counts, however, were somewhat lower (up to 1.7 x 10(3)/g). The high contamination rate of cooked or hot smoked foods suggests recontamination after cooking or smoking, e.g., at the slicing and packaging stage. 61.2% of the identified strains were Aeromonas hydrophila, followed by 22.5% Aeromonas caviae and 16.3% Aeromonas sobria.