Different food samples collected from randomly selected retail consumer shops in Uppsala (Central Sweden) were investigated for the presence of Aeromonas species. Forty-two percent (10/24) of the food samples contained organisms belonging to two Aeromonas spp. namely, Aeromonas hydrophila and Aeromonas sobria. The type of foods from which Aeromonas were isolated, were poultry, fish, beef and pork. None of the Aeromonas spp. were isolated from vegetables or raw milk samples. The Aeromonas isolates possessed the capacity to produce different potential virulence determinants such as haemolysin, cytotoxin, cytotonic toxin, enterotoxin and protease. Since A. hydrophila and A. sobria are considered to be potential human pathogens, it is concluded that in case foodborne infections are suspected or encountered, the role of Aeromonas should not be ruled out.

Drinking water from three different municipal distribution systems in Sweden was investigated for the occurrence of Aeromonas spp. and identification of virulence factors of these organisms. Twenty-three of the 27 samples (85%) from the three distribution systems were positive for presumptive Aeromonas with a maximum of 860 cfu/100 ml drinking water. Of the 61 randomly selected presumptive Aeromonas isolates, 41 were identified as A. hydrophila and 20 as A. sobria. These Aeromonas isolates produced a variety of potential virulence factors such as haemolysin, cytotonic- and cytotoxic-toxin, enterotoxin and protease. These findings on the presence of Aeromonas in municipal drinking water supplies in Sweden show that the consumer can be exposed to high number of aeromonads. However, more epidemiological information needs to be gathered in this regard to elucidate their public health significance.

The PhenePlate (PhP) system for biochemical fingerprinting is based on analysis of the kinetics of biochemical tests in microplates. This was evaluated for typing Aeromonas spp. isolates from drinking water and food and 78 Aeromonas strains isolated on different occasions over 6 months from three public drinking water systems. The system was highly discriminating and the diversity index, as calculated from 65 unrelated isolates, was 0.993, and 53 different biochemical phenotypes (BPTs) were found. Food isolates were more homogeneous than random Aeromonas strains and identical isolates were sometimes found in food of different origin. Each public drinking water system contained several BPTs but some of these were dominant at several sampling sites and on several sampling occasions in a system. The PhP system is suitable for typing Aeromonas strains from food and water. It is simple to handle and can be used with large numbers of isolates.