Diversity and dynamic changes of intestinal microbial community in preterm infants with necrotizing enterocolitis

This study aimed evaluate the diversity and dynamics change of intestinal microbial community in preterm infants with necrotizing enterocolitis (NEC). Forty-two preterm infants were selected for fecal sample analysis, including 21 preterm infants with NEC and 21 healthy preterm infants. The diversity and dynamic changes of intestinal microbial community were explored through 16S rDNA PCR-denaturing gradient gel electrophoresis (DGGE). TA cloning Kit and sequencing were used to assess bacterial distribution and identify common dominant bacteria in preterm infants with NEC. Shannon index values for NEC stages I, II, and III were 2.01 +/- 0.73, 1.93 +/- 0.27, and 1.54 +/- 0.36, respectively; the marched control groups CI, CII, and CIII showed 2.65 (+/-) 0.26, 2.74 +/- 0.16, and 2.56 +/- 0.22, respectively. Shannon index of intestinal bacteria in the NEC group was significantly lower than that of the control group (P<0.05); meanwhile, Shannon index of NEC stage III was significantly lower than values obtained for NEC stages I and II (P<0.05). After treatment and gradual recovery, Shannon index of the NEC group was gradually increased and almost reached control values. There was no significant difference in the main bacterial types between NEC and control groups based on 16S rDNA PCR-DGGE, but Bifidobacterium, Lactobacillus and Escherichiacoli proportions in the NEC group were lower compared with control values. In contrast, Klebsiella and Bacteroides spp. Proportions were higher than those of the control group. The types and amounts of intestinal bacteria (especially probiotics) were reduced, but Klebsiella levels were increased, which might be an important factor in the pathogenesis of NEC.