Identification of low levels of heat labile enterotoxin in Escherichia coli from children with diarrhoea.

Out of 40 children with gastroenteritis and massive growth of E. coli in faeces, 7 yielded growth of E. coli strains producing heat-labile enterotoxin (LT), as identified by enzyme-linked immunosorbent assay (ELISA) using anticholera toxin coated plates or ganglioside coated plates. The toxin production in vitro was low, and decreased upon subculturing for 3 months in the laboratory. Only two of the strains were identified as LT-positive by the YI adrenal cell test. In addition, an LT-producing strain was isolated from an adult who had recently returned from Jordan. Sonication of the strains after subculturing released cell-bound LT. The clinical importance of such low toxin producing E. coli strains is not known.