Production of a phosphatidylglycerol-like substance by genital flora bacteria.

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.