Enterotoxin-producing bacteria isolated from Swedish travellers with diarrhoea

The isolation rate of bacterial enteropathogens of different species, particularly enterotoxin-producing Gram-negative bacteria, was determined in stool specimens from Swedish travellers with diarrhoea. Overall, bacterial enteropathogens were identified in 101 (47%) of the 217 travellers on their return home. The most common isolates were enterotoxin-producing bacteria (20%), Salmonellae (18%) and Campylobacter (8%), whereas Shigellae (3%) and Yersinia (0.5%) were rarely identified. Mixed infections were only found in 8 (4%) of the stool specimens. Enterotoxigenic bacteria of Escherichia coli (ETEC), Klebsiella, Morganella, Citrobacter, Pseudomonas and EF-group 10 species were identified. ETEC accounted for 37/43 (86%) enterotoxin-producing strains, and among them 54% produced heat-stable enterotoxin (ST) alone, 16% heat-labile enterotoxin (LT) alone and 30% both LT and ST. Four of the enterotoxin-producing non-E. coli strains produced ST and 2 produced LT alone. The isolation rate of enterotoxin-producing bacteria was somewhat higher in travellers visiting Africa, Asia and Latin America (24%) than in those travelling to Southern Europe (14%). Salmonellae, on the other hand, were identified in stools significantly more often after travel to Southern Europe (26%) than to various subtropical and tropical areas (12.5%).