<i>Lactobacillus murinus</i> HF12 colonizes neonatal gut and protects rats from necrotizing enterocolitis

The use of lactobacilli in prevention of necrotizing enterocolitis (NEC) is hampered by insufficient knowledge about optimal species/strains and effects on intestinal bacterial populations. We therefore sought to identify lactobacilli naturally occurring in postnatal rats and examine their ability to colonize the neonatal intestine and protect from NEC. L. murinus, L. acidophilus, and L. johnsonii were found in 42, 20, and 1 out of 51 4-day old rats, respectively. Higher proportion of L. murinus in microbiota correlated with lower NEC scores. Inoculation with each of the three species during first feeding significantly augmented intestinal populations of lactobacilli four days later, indicating successful colonization. L. murinus, but not L. acidophilus or L. johnsonii, significantly protected against NEC. Thus, lactobacilli protect rats from NEC in a species- or strain-specific manner. Our results may help rationalizing probiotic therapy in NEC.乳杆菌属（lactobacilli）用于预防坏死性小肠结肠炎（Necrotizing Enterocolitis, NEC）的应用，因学界对其最优菌种/菌株及对肠道菌群的影响认知不足而受阻。为此，本研究旨在鉴定产后大鼠体内天然存在的乳杆菌属菌株，并探究其在新生大鼠肠道内的定植能力以及对坏死性小肠结肠炎的防护作用。在51只4日龄大鼠中，分别有42只、20只和1只检出鼠乳杆菌（L. murinus）、嗜酸乳杆菌（L. acidophilus）和约氏乳杆菌（L. johnsonii）。肠道菌群中鼠乳杆菌的相对丰度与坏死性小肠结肠炎评分呈显著负相关。在首次喂养时对大鼠接种这三种乳杆菌中的任意一种，均可在4天后显著提升肠道内乳杆菌的数量，表明接种成功实现了肠道定植。仅鼠乳杆菌（L. murinus）可显著发挥抗坏死性小肠结肠炎的防护作用，而嗜酸乳杆菌（L. acidophilus）和约氏乳杆菌（L. johnsonii）则无此防护效果。由此可见，乳杆菌属细菌对坏死性小肠结肠炎的防护作用具有菌种或菌株特异性。本研究结果可为坏死性小肠结肠炎的益生菌治疗方案提供合理化参考依据。