Abstract：
Infants have digestive environments that are more favorable for microbial proliferation and subsequent endogenous nitrite production than those of adults, but direct evidence of this has been lacking. In this study, we propose a novel epidemiology of infant methemoglobinemia by demonstrating the risk posed by nitrite-producers in the gastrointestinal tract. Nitrite-producers from vegetables (n = 323) were exposed to stress factors of the gastrointestinal environment (gastric pH, intestinal bile salts, anaerobic atmosphere) reflecting 4 different postnatal age periods (Neonate, ≤1 month; Infant A, 1-3 months; Infant B, 3-6 months; Infant C, 6-12 months). \"High-risk\" strains with a nitrate-to-nitrite conversion rate of ≥1.3 %, the minimum rate corresponding to nitrite overproduction, under the Neonate stress condition were analyzed for intestinal adhesion. Among all the phyla, Pseudomonadota achieved the highest survival (P < 0.05; survival rate of 51.3-71.8 %). Possible cross-protection against bile resistance due to acid shock was observed for all the phyla. All the high-risk strains exhibited moderate autoaggregation (14.0-36.4 %), whereas only a few exhibited satisfactory surface hydrophobicity (>40 %). The Pantoea agglomerans strain strongly adhered to Caco-2 cells (7.4 ± 1.1 %). This study showed the ability of the Pantoea, Enterobacter, and Klebsiella strains to survive under gastrointestinal stress for ≤12 months, to excessively produce nitrite under neonatal stress conditions, and to settle in the human intestine. To our knowledge, this is the first study to reveal the role of the natural flora of vegetables in the epidemiology of infant methemoglobinemia through a multilateral approach.
摘要：
婴儿的消化环境比成年人更有利于微生物增殖和随后的内源性亚硝酸盐产生，但缺乏这方面的直接证据。在这项研究中,我们提出了一种新的婴儿高铁血红蛋白血症的流行病学，通过证明胃肠道中亚硝酸盐产生者带来的风险。来自蔬菜的亚硝酸盐生产者（n=323）暴露于胃肠环境的应激因素（胃pH，肠道胆汁盐，厌氧气氛)反映4个不同的出生后年龄(新生儿，≤1个月；婴儿A，1-3个月；婴儿B，3-6个月；婴儿C，6-12个月）。硝酸盐至亚硝酸盐转化率≥1.3%的“高风险”菌株，与亚硝酸盐过量生产相对应的最小速率，在新生儿应激条件下进行肠粘连分析。在所有的门中，Pseudomonadota的存活率最高（P<0.05；存活率为51.3-71.8％）。在所有门中都观察到了由于酸休克引起的针对胆汁抗性的交叉保护。所有高危菌株均表现出中度自聚集（14.0-36.4％），而只有少数表现出令人满意的表面疏水性(>40%)。泛菌团块菌株强烈粘附于Caco-2细胞(7.4±1.1%)。这项研究表明泛菌的能力，肠杆菌,和克雷伯菌菌株在胃肠应激下存活≤12个月，在新生儿应激条件下过度产生亚硝酸盐，并在人体肠道中定居。据我们所知,这是第一项通过多边方法揭示蔬菜天然菌群在婴儿高铁血红蛋白血症流行病学中的作用的研究。
