Abstract:

Objective To analyze the effect of empirical antibiotic therapy on the intestinal microbiota of preterm infants and its dynamic change by 16S rDNA PCR-denaturing gradient gel electrophoresis(DGGE).Methods In the period from January 2014 to January 2015, twenty-four hospitalized preterm infants in Children′s Hospital of Chongqing Medical University were enrolled and divided into piperacillin-tazobactam treatment (PT) group and antibiotic free (AF) group. The meconium and fecal samples on d3, d5 and d7 were collected during the first week of life. After DNA extraction and PCR amplification, the microbial community diversity was analyzed through DGGE fingerprints. The distributions of common dominant bacteria were investigated by TA cloning and sequencing.Results A total of 96 fecal samples were analyzed. The amplification of bacterial DNA from 24 meconium (＜12 h) was failed and DGGE analysis was not performed. ①The median (P25-P75) of Shannon index of PT group on d3, 5 and 7 was 1.64 (1.16-1.92)、1.97 (1.69-2.20) and 1.22 (0.69-2.1) respectively, and that of AF group at the same time point was 1.39 (0.94-1.94)、2.24 (2.07-2.49) and 2.38 (2.07-2.61). On d3 and d5 of postnatal life, PT and AF infants did not differ in the diversity index of the fecal bacterial community, but on d7, the Shannon index of PT group was significantly lower than that of the AF group(P<0.05). ②The result of DGGE at all the 3 time points showed that the Shannon index of AF group gradually increased during the first week of life, while the Shannon index of PT group had a tendency of decrease. ③The bacterial composition on day 7 from DGGE fingerprint showed that Klebsiella sp. was dominant (35.5% and 42.4%) and the proportion of lactobacillus sp. was low (1.6% and 0.8%)in both groups. The proportions of Enterococcus sp. and Streptococcus sp. in PT group were higher (21.0% vs 7.2%,25.8% vs 4.0%), while the proportion of Enterobacter sp. was lower than that of AF group (3.2% vs 12.8%). Veillonella sp. and Clostridium sp. could only be detected in the AF group.Conclusion The gut microbiota of preterms has a simple structure. The antibiotic therapy can reduce the diversity.