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Production of a phosphatidylglycerol-like substance by genital flora bacteria
J G Pastorek1, R L Letellier, K Gebbia
1Department of Obstetrics and Gynecology, Louisiana State University Medical Center, New Orleans 70112-2822.
Abstract:
Bacteria contaminating amniotic fluid have anecdotally been shown to produce a phosphatidylglycerol-like substance, thus giving false positive tests for phosphatidylglycerol in vaginal pool fluid from patients with premature rupture of the membranes. Isolates of Escherichia coli, Proteus mirabilis, Acinetobacter calcoaceticus, Klebsiella pneumoniae, Staphylococcus aureus, coagulase-negative Staphylococcus, Streptococcus faecalis, and Streptococcus agalactiae (group B streptococcus) were grown in broth and analyzed for the presence of phosphatidylglycerol-like material by one-dimensional thin-layer chromatography and also by a polyclonal, immunologic slide agglutination test (Amniostat-FLM). All species demonstrated a positive test result for phosphatidylglycerol by either thin-layer chromatography, slide agglutination, or both. The material migrated separately from cardiolipin and phosphatidylethanolamine as determined by chromatography, but identically with the phosphatidylglycerol control. Gram-negative species were more strongly positive than gram-positive organisms. Colony counts on the order of 10(8) colony-forming units per milliliter were necessary to give positive test results for phosphatidylglycerol. The possible clinical implications of these findings are discussed.
Insights
Bacterial contamination in amniotic fluid can yield false positive phosphatidylglycerol (PG) tests, crucial for premature rupture of membranes diagnosis. This study confirms various bacteria produce PG-like substances, impacting diagnostic accuracy.
Area of Science:
- Microbiology
- Clinical Chemistry
- Obstetrics
Background:
- Phosphatidylglycerol (PG) is a key biomarker for fetal lung maturity.
- Premature rupture of membranes (PROM) testing relies on accurate PG detection.
- Bacterial contamination of amniotic fluid is a known complication.
Purpose of the Study:
- To investigate if common amniotic fluid bacteria produce phosphatidylglycerol-like substances.
- To determine if bacterial production of PG-like material can cause false positive diagnostic tests.
Main Methods:
- Bacterial isolates (e.g., E. coli, S. aureus, GBS) were cultured.
- Thin-layer chromatography and immunologic slide agglutination (Amniostat-FLM) were used to detect PG-like material.
- Colony counts were correlated with test results.
Main Results:
- All tested bacterial species produced a substance mimicking PG.
- Gram-negative bacteria showed stronger positive results than Gram-positive bacteria.
- High bacterial concentrations (around 10^8 CFU/mL) were needed for positive PG tests.
Conclusions:
- Bacterial contamination can lead to false positive PG tests in PROM diagnosis.
- This phenomenon may affect the interpretation of fetal lung maturity tests.
- Clinical awareness of bacterial interference is crucial for accurate diagnosis.