OBJECTIVETo study the relationship between microbial gene 16SrRNA and intrauterine infection.

METHODSThirty cases of single preterm birth were enrolled, including 16 cases due to premature rupture of membranes (PROM) (rupture time>18 hrs), 6 cases due to spontaneous preterm birth and 8 cases due to iatrogenic preterm birth. Ten cases of single term birth were used as the control group. Fetal membrane and placenta samples were obtained. Amniotic fluid, blood from cord or newborn babies as well as gastric fluid and tracheal secretions from infants with mechanical ventilation were also obtained. The histological features of placenta and fetal membranes were observed. Polymerase chain reaction (PCR) was used to detect the presence of microbial 16SrRNA and ureaplasma urealyticum (UU) in placenta, fetal membranes and other samples.

RESULTSTwenty-one (70%) cases were diagnosed as chorioamnionitis, characterized by neutrophil infiltration in fetal membrane and placenta tissues, especially in fetal membranes. Chorioamnionitis was most frequent in babies whose gestational age less than 32 weeks or birth weight lower than 1 500 g. Positive 16SrRNA gene was found in 12 cases, and positive UU gene in 10 cases in the preterm birth group. Neither 16SrRNA nor UU gene was detected in the control group. The PROM preterm babies developed more frequent infection than the babies premature born due to other causes, but there were no statistically significant differences in the incidence of infection.

CONCLUSIONSChorioamnionitis may be the major cause of PROM and premature birth. The detection of microbial genes is valuable in identification of intrauterine infection.