Escherichia coli SA53 produces a new enterotoxin that has a biological activity similar to that of E. coli heat-labile enterotoxin (LT) but is not neutralized by antiserum against LT or cholera enterotoxin. Strain SA53 contained two plasmids, pRB1 (69.2 +/- 4.3 megadaltons) and pRB2 (57.6 +/- 5.3 megadaltons). Studies were undertaken to determine whether either plasmid was required for producti...

The aim of this study was to determine the occurrence of enterotoxigenic and enteroaggregative Escherichia coli strains and antibiotic resistance of the isolates in raw milk and unpasteurized cheese. Out of 200 samples of raw milk and 50 samples of unpasteurized cheeses, 96 and 24 strains of E. coli were isolated, respectively. Polymerase chain reaction (PCR) was used to detec...

Rats immunized with a semipurified preparation of the Escherichia coli heat-stable (ST) enterotoxin conjugated with a protein carrier were protected against challenge with semipurified or purified ST and viable organisms of multiple heterologous serotypes that produce only ST (LT-/ST+), but they were not protected against heal-labile (LT) toxin or viable strains which produce LT either alone (L...

Heat-labile enterotoxins from Escherichia coli strains of porcine and human origin polymerize on heating to form high-molecular-weight aggregates, "procoligenoids," analogous to procholeragenoid derived from the cholera enterotoxin. This aggregation is accompanied by loss of biological activity (toxicity). Further heating results in the release of B-subunit oligomers, coligenoids, analogous to ...

Heat-labile enterotoxin (LT) was purified from an enterotoxigenic Escherichia coli 015H11 of human origin. The purification steps included French pressure cell disruption of the bacteria, salting-out, DEAE-Sephacel on chromatography. Application of this procedure resulted in a 95.1-fold purification of LT with a yield of 19.9% as determined by rabbit ileal loop assay. The final LT preparation s...

A temperate phage designated obeta1 (omicron beta) was mitomycin C induced and isolated from heat-labile enterotoxin (LT)-producing Escherichia coli E2631-C2. Phage obeta1 infected the nonlysogenic, nontoxigenic, mitomycin C-sensitive strain of E. coli K-12 (CSH38) and converted it to lysogeny and enterotoxigenicity. After the establishment of lysogeny, E. coli CSH38(obeta1) produced produced L...