POTENTIAL SOURCES OF HUMAN LISTERIOSIS IN SWEDEN

Altogether 68 Listeria monocytogenes strains belonging to serovar 1/2a isolated from human cases of listeriosis, salmon, rainbow trout and s oft cheeses were further characterized to find out if these food produ cts could be connected with human listeriosis in Sweden. Phagetyping a nd restriction endonuclease analysis (REA) with pulsed-field gel elect rophoresis (PFGE) were used for characterization of the strains. Twent y-three strains belonging to phagovar 1 and five strains belonging to the closely related phagovar 24 were selected for REA and PFGE. L. mon ocytogenes isolates from two humans and two fish products shared the s ame PFGE pattern. The same was true for three human isolates and one s almon isolate. These findings suggest that there may be an association between human cases of listeriosis and consumption of salmon or rainb ow trout. None of the soft cheese isolates were identical with the hum an strains. (C) 1998 Academic Press Limited.