ANTIMICROBIAL EFFECT OF ACIDIFIED NITRITE ON GUT PATHOGENS - IMPORTANCE OF DIETARY NITRATE IN HOST-DEFENSE

Dietary intake of nitrate generates salivary nitrite, which is acidifi ed in the stomach, leading to a number of reactive intermediates of ni trogen, among which are the potentially carcinogenic N-nitrosamines. A cidified nitrite, however, also has antimicrobial activity which coinc ides with the formation of nitric: oxide. The present study examines t he antimicrobial effect in vitro of acidified nitrite on Salmonella en teritidis, Salmonella typhimurium, Yersinia enterocolitica, Shigella s onnei, and Escherichia coli O157, First-order regression plots showed a linear inverse relationship of log-transformed proton and nitrite co ncentrations with MICs and MBCs after 30 min, 2 h, and 24 h of exposur e (P < 0.001 for all antibacterial activities), Susceptibility to the acidified nitrate solutions ranked as follows: Y. enterocolitica > S, enteritidis > S. typhimurium = Shigella sonnei > E, coli 0157 (P < 0.0 5), Addition of SCN-, but not that of Cl-, increased the antibacterial activity (paired t testing, P < 0.001), Generation of salivary nitrit e from dietary nitrate may provide significant protection against gut pathogens in humans.