Effects of lincomycin and tetracycline on production and properties of enterotoxins of enterotoxigenic Escherichia coli.

Enterotoxigenic Escherichia coli grown in the presence of lincomycin and tetracycline produced an increased amount of heat-labile enterotoxin (LT). These antibiotics increased the production of not only extracellular LT but also intracellular LT. On the other hand, lincomycin did not stimulate the production of heat-stable enterotoxin by enterotoxigenic E. coli. The extracellular LTs produced in the presence of lincomycin and tetracycline were purified and analyzed by sodium dodecyl sulfate-polyacrylamide gel disc electrophoresis. Results showed that the A subunits of the purified LTs were not nicked, unlike that of extracellular LT produced in the absence of the antibiotics.