Microbiome of the placenta in pre-eclampsia supports the role of bacteria in the multifactorial cause of pre-eclampsia.

Aim: This study was aimed at detecting, identifying, quantifying and comparing the bacteria present in the placental tissues of women with pre-eclampsia with that of normotensive pregnant women.

Material And Methods: Placental tissue samples were collected from 55 primiparous women with pre-eclampsia (cases) and 55 matched primiparous normotensive pregnant women (controls) at the time of delivery by cesarean section. Genotyping was carried out in two stages. First the samples were screened for the presence of bacteria by polymerase chain reaction (PCR) for the 16S rRNA gene. Next, the samples that were PCR-positive for the 16S rRNA gene were screened by next-generation sequencing on an Illumina MiSeq platform.

Results: Seven (12.7%) placental tissue samples from women with pre-eclampsia were PCR-positive. All the placental samples from control women were negative (P = 0.006). The complete microbiome of the seven samples was revealed through next-generation sequencing. The organisms that were present included Bacillus cereus, Listeria, Salmonella, Escherichia (all of which are usually associated with gastrointestinal infection); Klebsiella pneumonia and Anoxybacillus (both of which are usually associated with respiratory tract infections); and Variovorax, Prevotella, Porphyromonas, and Dialister (all of which are usually associated with periodontitis).

Conclusions: This study confirms the presence of bacteria in the placental tissues of a subset of women with pre-eclampsia and supports the role of bacteria in the multifactorial cause of pre-eclampsia.