ISOLATION, AND VIRULENCE PROFILES, OF AEROMONAS-HYDROPHILA IMPLICATEDIN AN OUTBREAK OF FOOD POISONING IN SWEDEN

A case of food poisoning outbreak involving Aeromonas hydrophila is re ported in this study. A group of 27 people consumed a typical Swedish food ''landgang'' which is a type of smorgasbord containing shrimps wi th mayonnaise, liver pate, ham, sausage, and legume salad which was pu rchased from a food store. Twenty-two of the 27 persons became ill wit hin 20-34 hr of consumption of the food and reported the symptoms rang ing from severe acute diarrhea, abdominal pain, headache, fever and vo miting. One person also fainted. The symptoms lasted for a couple of d ays. Of the remaining 5 healthy persons who consumed the left-over foo d the next day, 2 became ill with similar symptoms, The bacteriologica l examination of left-over food samples resulted in the isolation of A . hydrophila from shrimps with mayonnaise, smoked sausage, liver pate and boiled ham. The total number of A. hydrophila in these foods were log 10(6) to log > 10(7) organisms per gram of food sample. A. hydroph ila was however, not isolated from legume/mayonnaise salad samples. Al l the food samples tested showed low numbers of other expected food co ntaminating organisms such as coliforms at 37 C and 44 C, fecal strept ococci, Staphylococcus aureus, fungi and yeast etc., while Bacillus ce reus, Clostridium perfringens and Salmonella spp. were not detected in the food samples. Investigations of the virulence profiles of the A. hydrophila isolates showed their capacity to produce beta-hemolysin, c ytotoxins, cytotonic toxins, enterotoxins, and adhesion to and invasio n of human intestinal (Henle 407) cells in culture.