Related Experiment Video
Updated: Jun 12, 2026
Human Placental and Decidual Organ Cultures to Study Infections at the Maternal-fetal Interface
Published on: July 21, 2016
Microbial invasion of the amniotic cavity in preeclampsia as assessed by cultivation and sequence-based methods
Daniel B DiGiulio1, Mariateresa Gervasi, Roberto Romero
1Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.
Objective:
Infection has been implicated in the pathogenesis of preeclampsia, yet the association between microbial invasion of the amniotic cavity (MIAC) and preeclampsia has not been determined. The aim of this study was to determine the prevalence, and microbial diversity associated with MIAC, as well as the nature of the host response to MIAC in patients with preeclampsia.
Method Of Study:
Amniotic fluid (AF) from 62 subjects with preeclampsia, not in labor, was analyzed with both cultivation and molecular methods. Broad-range and group-specific PCR assays targeting small subunit ribosomal DNA, or other gene sequences, from bacteria, fungi and archaea were used. Results were correlated with measurements of host inflammatory response, including AF white blood cell count and AF concentrations of glucose, interleukin-6 (IL-6) and MMP-8.
Results:
1) The rate of MIAC in preeclampsia was 1.6% (1/62) based on cultivation techniques, 8% (5/62) based on PCR, and 9.6% (6/62) based on the combined results of both methods; 2) among the six patients diagnosed with MIAC, three had a positive PCR for Sneathia/Leptotrichia spp.; and 3) patients with MIAC were more likely to have evidence of an inflammatory response in the amniotic cavity than those without MIAC, as determined by a higher median AF IL-6 [1.65 ng/mL interquartile range (IQR): 0.35-4.62 vs. 0.22 ng/mL IQR: 0.12-0.51; P=0.002).
Conclusion:
The prevalence of MIAC in preeclampsia is low, suggesting that intra-amniotic infection plays only a limited role in preeclampsia. However, the unexpectedly high number of positive AF specimens for Sneathia/Leptotrichia warrants further investigation.
Insights
Microbial invasion of the amniotic cavity (MIAC) is uncommon in preeclampsia, occurring in less than 10% of cases. However, MIAC is associated with increased amniotic fluid inflammation, particularly IL-6 levels.
Area of Science:
- Perinatology
- Infectious Disease
- Reproductive Immunology
Background:
- Preeclampsia pathogenesis is complex, with infection proposed as a contributing factor.
- The role of microbial invasion of the amniotic cavity (MIAC) in preeclampsia remains unclear.
Purpose of the Study:
- To determine the prevalence and microbial diversity of MIAC in preeclampsia.
- To investigate the host inflammatory response to MIAC in preeclampsia patients.
Main Methods:
- Amniotic fluid from 62 preeclampsia patients was analyzed using cultivation and PCR.
- Broad-range PCR targeted bacteria, fungi, and archaea.
- Inflammatory markers (WBC, glucose, IL-6, MMP-8) were correlated with MIAC findings.
Main Results:
- MIAC prevalence was 9.6% by combined methods.
- Sneathia/Leptotrichia spp. were identified in three cases.
- MIAC was associated with significantly higher amniotic fluid IL-6 levels (P=0.002).
Conclusions:
- MIAC is infrequent in preeclampsia, suggesting a limited role in the condition's overall pathogenesis.
- The association of MIAC with intra-amniotic inflammation warrants further investigation, especially concerning Sneathia/Leptotrichia.
