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Bacterial attachment to the chorioamniotic membranes
Abstract:
Intra-amniotic infections are believed to result from bacteria of cervical and vaginal origin which gain access to the amniotic sac. The logical sequence in this process would be bacterial attachment to the maternal surface, followed by migration through the chorioamniotic membranes to the fetal surface. Fresh sterile chorioamniotic membranes were interposed between two arms of specially constructed incubation vessels. Bacteria (Escherichia coli, group B streptococci, or Neisseria gonorrhoeae) were inoculated into the arm (containing a basal salt medium) contiguous with the maternal surface. The arm contiguous with the fetal surface of the membrane contained pseudoamniotic fluid. At intervals up to 24 hours after inoculation, the membranes were removed, washed, fixed in glutaraldehyde, and examined by means of scanning and transmission electron microscopes. The ability of group B streptococci and E. coli to attach to and invade the chorioamniotic membranes was demonstrated by this technique. It appeared that group B streptococci had a greater capacity to attach and invade than did E. coli, whereas N. gonorrhoeae predictably failed to attach.
Insights
This study demonstrates how bacteria like group B streptococci and E. coli can invade chorioamniotic membranes, a key step in intra-amniotic infections. Group B streptococci showed a higher invasion capacity than E. coli.
Area of Science:
- Obstetrics and Gynecology
- Microbiology
- Infectious Diseases
Background:
- Intra-amniotic infections (IAI) are a significant cause of maternal and neonatal morbidity.
- IAI are hypothesized to originate from ascending bacteria from the cervix and vagina.
- Understanding bacterial interaction with chorioamniotic membranes is crucial for IAI pathogenesis.
Purpose of the Study:
- To investigate the in vitro attachment and invasion capabilities of common bacterial pathogens to human chorioamniotic membranes.
- To model the initial stages of bacterial colonization within the amniotic sac.
Main Methods:
- Utilized a novel ex vivo incubation system with sterile human chorioamniotic membranes.
- Inoculated maternal-facing side with Escherichia coli, group B streptococci, or Neisseria gonorrhoeae.
- Examined membrane-bacteria interactions using scanning and transmission electron microscopy up to 24 hours post-inoculation.
Main Results:
- Demonstrated the capacity of group B streptococci and E. coli to attach to and invade the chorioamniotic membranes.
- Group B streptococci exhibited a greater ability to attach and invade compared to E. coli.
- Neisseria gonorrhoeae did not demonstrate attachment to the membranes under these conditions.
Conclusions:
- The study provides direct evidence of bacterial invasion through chorioamniotic membranes in vitro.
- Findings highlight the differential invasive potential of bacteria implicated in IAI.
- This model offers insights into the early mechanisms of intra-amniotic infection development.