Shotgun metagenomic screening to improve the retrospective diagnosis of undocumented intrauterine infections on embedded placenta samples: Lessons from a brucellosis case.

BACKGROUND

Microbiological diagnosis of intrauterine infections (IIU) still relies on bacteriological cultures or targeted DNA amplification lacking in sensitivity. Shotgun metagenomics (SMg) is an emerging unbiased molecular approach that makes it possible to sequence all the nucleic acids from any sample. It had never previously been used for IIU.

METHODS

We here report the case of a patient with an unexplained IIU and fetal loss that could be documented by a combined SMg/microbiological approach, leading to the diagnosis of maternal brucellosis.

RESULTS

A 31-year-old woman presented with an undocumented IIU with fetal loss at 24 weeks of gestation. Culture-based work-up failed to identify the pathogen involved. Paraffin-embedded placenta sample was retrospectively analyzed by SMg. Brucella spp nucleic acids were detected, and subacute maternal brucellosis was confirmed by targeted PCR and serological testing.

CONCLUSION

This case provides grounds for further utilization of SMg for the microbiological diagnosis of unexplained obstetrical infections.