Investigation Of The Intestinal Microbial Community Diversity And Dynamic Change In Preterm Infants With Necrotzing Enterocolitis

PartⅠ: Analysis the diversity of intestinal microbialcommunity and it,s dynamic change in preterm infants withnecrotizing enterocolitis by PCR-DGGE【Objective】To analysis the diversity of intestinal microbialcommunity and it,s dynamic change in preterm infants with necrotizingenterocolitis (NEC) by16S rDNA PCR denaturing gradient gelelectrophoresis（PCR-DGGE）.【Methods】 Preterm infants diagnosed with NEC during August2009to December2012in Chongqing Medical University affiliatedChildren’s Hospital and Children’s Hospital of ShenZhen were groupedinto NEC group, and divided it into three subgroups according to phaseⅠ、 Ⅱa ndⅢ;each group included7infants. Preterm infants without NECin the two hospital during the same period were grouped into the controlgroup,which were selected by matching the gestational age, days of age,birth weight with the7infants in each NEC subgroup;control group Ⅰ、Ⅱ、Ⅲ respectively matched with NEC group Ⅰ、Ⅱ、Ⅲ. The stool samples of the NEC infants were collected after admission of1、3、5、7and9day point.Analysis the Species richness S and Shannon index ofthem from their DNA amplification and DGGE by Quantity One software.【Results】①T he Speciesrichness S of NEC groupⅠ、Ⅱ、Ⅲ in1day after admission was respectively7.57±0.53、7.14±1.77、5.00±1.73，which were lower than those of the matched control group (respectivelywas14.71±3.82、15.86±2.61、13.29±2.75，P<0.05）;the Shannon indexof NEC groupⅠ、Ⅱ、Ⅲ in1day after admission was respectively2.01±0.73、1.93±0.27、1.54±0.36, which were lower than those of thematched control group (respectively was2.65±0.26、2.74±0.16、2.56±0.22,P <0.05); and in NEC stage Ⅲ,the Species richness S andShannon index were lower than those of NEC stage Ⅰ and NEC stageⅡ (P<0.05).②There were10infants in NEC group and10infants in matchedcontrol group which were obtained all of the5day points of stoolsamples.The diversity of dynamic change rule showed that the Shannonindex of the control group was keeping relatively stable level and theShannon index of NEC group was rising gradually with the admission timedelay,and after9days the Shannon index of NEC group was almost similarto that of the control group,P>0.05.【Conclusion】The decrease of the diversity in intestinal microbialcommunity might be an important factor in the pathogenesis of NEC;andthe diversity of intestinal microbial community might be associated withthe situation of the disease. Part Ⅱ: Investigation of the Bacterial species in preterminfants with necrotizing enterocolitis by TA cloning Kit andsequencing【Objective】To Investigate the distribution of bacteria and commomdominant bacteria in preterm infants with necrotizing enterocolitis.【Methods】The dominant bands from DGGE of infants’ fecal1dayafter admission were studied. The result from T-A cloning and sequencingwere comparatively analyzed on Http://blast. ncbi.nlm.nih.gov/Blast.【Results】The result of molecular coling and sequencing fromDGGE showed that the main bacterial types of NEC and control groupwere no difference,but the proportion of Bifidobacterium,Lactobacillusand Escherichia coli in NEC group were lower than those of the controlgroup,whlie the proportion of Klebsiella and Bacteroides sp. were higherthan those of the control group.【Conclusion】The decrease of probiotics leading to the relativedominance of klebsiella might be an important factor in the pathogenesisof NEC.