Chlorhexidine did not inhibit ATPase in intact cells of Escherichia coli K12 W1317i-, even at bactericidal concentrations, and ATP hydrolysis was greatest at the highest concentration (40 mg/l), even though no net uptake of substrate occurred. Like dinitrophenol and tribrominated salicylanilide, polymyxin and chlorhexidine collapsed the membrane potential at inhibitory concentrations. Membrane disruption, and not ATPase inactivation, is considered the lethal event in chlorhexidine action.

A large amount of cholera toxin (CT) was produced by Vibrio cholerae 01 cultured in yeast extract-peptone water. The organisms were cultured initially in a stationary test tube (small surface-to-volume ratio) until the end of the exponential phase and subsequently cultured in a shaking flask for 15 to 20 h. By this method (previously reported as the AKI-SW method), most cholera vibrios produced an abundance of CT (up to 64 ,ig/ml), regardless of their biotype and serotype. A substantial amount of CT was produced even in basic peptone water (2% peptone, 0.5% NaCi). Use of sodium bicarbonate, which markedly stimulated CT production in the stationary test tube culture, was undesirable for CT production by the culture method used here. CT production was greatly influenced by culture conditions but was not significantly affected by the composition of the medium.

No abstract

Chlorhexidine did not inhibit ATPase in intact cells of Escherichia coli K12 W1317i−, even at bactericidal concentrations, and ATP hydrolysis was greatest at the highest concentration (40 mg/l), even though no net uptake of substrate occurred. Like dinitrophenol and tribrominated salicylanilide, polymyxin and chlorhexidine collapsed the membrane potential at inhibitory concentrations. Membrane disruption, and not ATPase inactivation, is considered the lethal event in chlorhexidine action.

Recently isolated Vibrio cholerae and Shigella pecies from 6 countries were examined for their drug sensitivities. The sensitivities of V. cholerae were characterized by a narrow inhibitory concentration ranges without any resistant strain. However, the sensitivities of Shigella species were variable and mostly resistant to tetracycline and ampicillin. Japanese isolates of Shigella species were relatively more sensitive to tetracycline and ampicillin than the isolates from the other countries. Indonesian isolates of Shigella species were relatively more resistant than those of the other countries, even to the new antimicrobials such as ofloxacin and cefdinir, and a highly resistant strain against ofloxacin was found.