Phosphate content of human amniotic fluid and its relationship to bacterial growth inhibition.

A sensitive method for assay of phosphate has been adapted for use with human amniotic fluid. The presence of an antibacterial factor in amniotic fluid inactivated by phosphate suggested that measurement of free phosphate may predict antibacterial activity and hence susceptibility to intrapartum infection. The intrinsic antibacterial activity of amniotic fluid was altered by addition of large amounts of phosphate, but the intrinsic concentration of free phosphate correlated poorly with antibacterial activity and organically combined phosphates did not appear to be related to the antibacterial property.