D. Omeara et al., COLORIMETRIC DETECTION OF HEAT-LABILE TOXIN-ENCODING GENE OF ENTEROTOXIGENIC ESCHERICHIA-COLI BY PCR, Journal of clinical microbiology, 33(7), 1995, pp. 1957-1960
In the developing world, enterotoxigenic Escherichia coli (ETEC) strai
ns which produce enterotoxins are a significant cause of morbidity and
mortality. Heat-labile (LT) toxin PCR detection methods have been des
cribed, but they have limited applications in a routine laboratory set
ting. A colorimetric DNA method for the rapid amplification and detect
ion of the LT toxin gene in ETEC strains is described. Target amplific
ation together with colorimetric detection would overcome many of the
limitations of conventional PCR. This paper describes a colorimetric P
CR detection method specific for LT-gene-encoding ETEC strains. DNA wa
s extracted from two representative colonies from each bacterial isola
te and amplified by PCR. Digoxigenin was incorporated into the amplifi
cation product, permitting a one-step direct detection using anti-digo
xigenin alkaline phosphatase-conjugated antibody. This technique was a
pplied to the investigation of 70 E. coli isolates derived from clinic
al fecal samples obtained from an Irish population. Eleven percent of
the samples were LT positive, confirming the applicability of this met
hod. All LT-positive ETEC strains (controls and clinical isolates) wer
e detected, and no false-positive results occurred.