Intestinal Microbial Community Diversity In Neonatal Necrotizing Enterocolitis Analyzed By PCR-DGGE

ObjectiveNeonatal necrotizing enterocolitis (NEC) is the acute abdomen innewborn especially preterm infants, with clinical manifestations ofabdominal distention, vomiting, bloody diarrhea, severe shock for theperformance and the X-ray characteristic of the intestinal cysticpneumatosis. The mortality of this disease in our country is about10%-50%,5%in the U.S. in term newborn, and in preterm newborn, especiallyof the weight <1000g,it is up to50%. NEC is a multifactorial disease,bacterial infections is one of the indispensable causal factor. Studies haveshown that the NEC has not yet occurred in the sterile animal models，itmeans no bacteria no NEC. It has been hypothesized that abnormalbacterial colonization of the neonatal gut is an important factor for NEC,especially anaerobic bacteria in the intestine begin planting growth in thenewborn within8-10days after birth. Yet, there is not a clear explanation ofthe NEC bacterial infection. In this study, we use the modern molecularbiology techniques to study the NEC gut microflora composition and dynamic change, and hope to provide bacteriological theoretical basis forthe pathogenesis of NEC and the prevention and treatment for thisdisease.Material and Method32cases were selected from the neonatal ward of the Children’sHospital from August to December in2009, the NEC group and controlgroup of16cases. The NEC group is charged according to diagnosticcriteria of Pediatrics, all patients had x-chip (+) and stool OBs (+) and werestage Ⅰaccording to international Walsh and Kliegman BELL stagingcriteria. Control group tried to match according to clinical characteristics:gender, gestational age, mode of production, feeding patterns, birth weight,use of antibiotics. Extract the total bacterial DNA of gut from fresh stool ofnewborn, conduct polymerase chain reaction amplification with16s rDNAV3variable region primers and then denaturing gradient gel electrophoresis.Sequence DNA recovered from DGGE plastic, and analysis intestinalbacterial diversity with Shannon index and sequence alignment.ResultsDGGE：13/16(81.25%) of the NEC group compared with thecontrol group, Shannon index of intestinal bacterial is relatively high andunevenly distributed, fluctuating significantly (the NEC group vs the controlgroup, P <0.05), and the bacteria diversity is higher. There are somedifferences in bacterial diversity features between the two groups. Shannon index of the NEC group increased significantly in the early stage, and downthen up with the treatment and recovery of the disease, and DNAsequencing recycling from DGGE plastic showed neonatal intestinaladvantage flora genus were Klebsiella pneumoniae, Escherichia coli,Enterococcus.Main types of the NEC and control groups was nosignificant difference, there are quantitative differences.3/16(18.75%) thetrend above and Shannon index difference are not obvious.ConclusionThis study indicated that NEC group existed imbalance in gut bacteria,which might be an important factor in NEC intestinal bacterial infections.