Comparison of Bacterial Composition in Blood and Placentas Using
Conventional and Molecular Methods

Fetus was considered to be sterile and little work is done to explore the ignored microbial diversity in it. To investigate the bacterial diversity in the feces, blood and placentas of pregnant mice and to assess the translocation capability of the administered strains, conventional culture and PCR denaturing gradient gel electrophoresis (PCRDGGE) were used in the present study. The culture method detected microbes (lactobacilli, enterobacter and enterococcus) in the blood and in the placentas at positive rates of 27.8%, 55.6% and 11.1% and 22.2%, 66.7% and 16.7%, respectively. The PCR-DGGE results showed that the E. faecalis, L. lactis and an uncultured bacterium were the dominant bacteria found in the feces, blood and placentas, and the transport of E. faecalis FD3 from the intestinal tract to the blood and to the placenta was also observed, revealing a potential risk to the health of both mother and fetus. In conclusion, the combination of classical cultivation and PCR-DGGE methods provides a superior strategy for the fast and accurate monitoring of the microbial composition in the blood and in the placentas of pregnant mice.