Comprehensive analysis of bacterial DNA has enhanced our understanding of the maternal microbiome and its disturbances in preterm birth although clinical utility of these techniques remains to be determined. We tested whether a broad-range polymerase chain reaction (PCR) technique is useful for detection of culture-negative intra-amniotic infection (IAI). Pregnant women who underwent amniocentesis for the management of preterm birth with or without premature rupture of membranes. Bacterial 16S ribosomal DNA in the amniotic fluid was detected by PCR using primers for a sequence shared by Ureaplasma, Mycoplasma, and other bacteria. Sixty-four women were enrolled, 9 of whom were culture-positive. Of the 55 culture-negative women, 13 were PCR-positive and exhibited significantly higher interleukin 6 and 8 levels and lower glucose levels in the amniotic fluid than the remaining 42 women did, who were PCR- and culture-negative. C-reactive protein concentrations were elevated in cord and neonatal blood in the culture-negative, PCR-positive subgroup, whereas maternal C-reactive protein concentrations, white blood cell counts, and body temperatures were alike. The placental inflammation score (Blanc stage≥2) was significantly higher in the PCR-positive than in PCR-negative subgroup. This PCR-based method could be useful for identifying bacterial-culture-negative subclinical IAI and could help with predicting the severity of IAI.
Keywords: amniotic infection; prenatal diagnosis; preterm birth; ribosomal DNA.