Broad-spectrum bacterial rDNA polymerase chain reaction assay for detecting amniotic fluid infection among women in premature labor.

We amplified bacterial 16S rRNA encoding DNA (rDNA) with the polymerase chain reaction (PCR) to detect amniotic fluid infection in 69 women in premature labor whose membranes were intact. Bacterial rDNA was detected by PCR in samples from 15 (94%) of 16 patients with positive amniotic fluid cultures. Bacteria were detected by PCR in samples from 5 (36%) of 14 patients with negative cultures and elevated interleukin (IL)-6 levels vs. 1 (3%) of 39 patients with negative cultures and IL-6 levels of < or = 2,000 pg/mL (P < .01). The median amniotic fluid cytokine levels and the pregnancy outcomes were similar for patients with positive amniotic fluid cultures and those with negative cultures and positive rDNA PCR assays. The association between amniotic fluid infection and premature labor may be underestimated on the basis of amniotic fluid culture results. The broad-spectrum bacterial 16S rDNA PCR assay may prove useful for diagnosing amniotic fluid infection.