Bacterial culture-negative subclinical intra-amniotic infection can be detected by bacterial 16S ribosomal DNA-amplifying polymerase chain reaction

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Comprehensive analysis of bacterial DNA enhanced our understanding of the maternal microbiome and its disturbance in preterm birth, although clinical utility of these techniques remains to be determined. We examined whether broad-range polymerase 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 the premature rupture of membranes. Bacterial 16S ribosomal DNA in the amniotic fluid was detected by polymerase chain reaction (PCR) using primers for a sequence shared by Ureaplasma, Mycoplasma, and other bacteria. Sixty-four women were enrolled, nine 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, who were PCR- and culture-negative. C-reactive protein was elevated in cord and neonatal blood in the culture-negative, PCR-positive subgroup, whereas maternal C-reactive protein, white blood cell count, and body temperature were alike. Placental inflammation score (Blanc stage ≥2) was significantly higher in PCR-positive than in PCR-negative subgroup. This PCR-based method could be useful in identifying bacterial culture-negative subclinical IAI and could help in predicting the severity of IAI.