Dykhuizen R S, Fraser A, McKenzie H, Golden M, Leifert C, Benjamin N
Department of Medicine and Therapeutics, Medical School, Forresterhill, Aberdeen, UK.
Gut. 1998 Mar;42(3):334-7. doi: 10.1136/gut.42.3.334.
Due to the expression of urease, Helicobacter pylori is able to establish itself in the human stomach under acidic conditions. A novel host defence mechanism was recently proposed, suggesting that the formation of salivary nitrite in symbiosis with facultative anaerobic bacteria in the oropharynx, is aimed at enhancing the antimicrobial activity of gastric juice.
To investigate whether the addition of nitrite in physiological concentrations influences the resistance of H pylori to acid.
H pylori cultured from fresh gastric Biopsy specimens was exposed for 30 minutes to normal saline and to HCl/KCl buffer (0.2M) at pH 2 with urea (5 mM) added. The influence of potassium nitrite (50-1000 mumol/l) on bacterial survival was determined.
Addition of nitrite (1 mM) to acidic solutions (pH 2) resulted in complete kill of H pylori within 30 minutes exposure time whereas acid alone allowed the organism to survive (p < 0.001). The antimicrobial effect of nitrite at pH 2 against H pylori was dose dependent and complete kill of organisms occurred at concentrations > or = 500 mumol/l.
Acidified nitrite has anti-bacterial activity against H pylori. This should prompt further research into the effect of salivary nitrite on the survival of H pylori in the human stomach.
由于脲酶的表达，幽门螺杆菌能够在酸性条件下在人胃中定植。最近提出了一种新的宿主防御机制，表明在口咽部与兼性厌氧菌共生时形成的唾液亚硝酸盐旨在增强胃液的抗菌活性。
研究添加生理浓度的亚硝酸盐是否会影响幽门螺杆菌对酸的抗性。
将从新鲜胃活检标本中培养的幽门螺杆菌暴露于生理盐水和添加了尿素（5 mM）的pH值为2的HCl/KCl缓冲液（0.2M）中30分钟。测定亚硝酸钾（50 - 1000 μmol/l）对细菌存活的影响。
在酸性溶液（pH 2）中添加亚硝酸盐（1 mM）会导致在30分钟的暴露时间内幽门螺杆菌全部被杀灭，而仅酸环境下该菌仍能存活（p < 0.001）。pH 2时亚硝酸盐对幽门螺杆菌的抗菌作用呈剂量依赖性，在浓度≥500 μmol/l时可完全杀灭细菌。
酸化亚硝酸盐对幽门螺杆菌具有抗菌活性。这应促使进一步研究唾液亚硝酸盐对幽门螺杆菌在人胃中存活的影响。
