Does the human placenta delivered at term have a microbiota? Results of cultivation, quantitative real-time PCR, 16S rRNA gene sequencing, and metagenomics

Theis KR1Romero R2Winters AD3Greenberg JM3Gomez-Lopez N4Alhousseini A5Bieda J6Maymon E7Pacora P6Fettweis JM8Buck GA9Jefferson KK10Strauss JF 3rd11Erez O12Hassan SS13.

The human placenta has been traditionally viewed as sterile, and microbial invasion of this organ has been associated with adverse pregnancy outcomes. Yet, recent studies that utilized sequencing techniques reported that the human placenta at term contains a unique microbiota. These conclusions are largely based on the results derived from the sequencing of placental samples. However, such an approach carries the risk of capturing background-contaminating DNA (from DNA extraction kits, polymerase chain reaction reagents, and laboratory environments) when low microbial biomass samples are studied.