Placental features of chorioamnionitis colonized with Ureaplasma species in preterm delivery.

Ureaplasma spp. is detected in the urogenital tract, including the vagina, cervix, chorioamnion, and placenta. Their colonization is associated with histologic chorioamnionitis (CAM), often observed in placentas from preterm delivery. We isolated Ureaplasma spp. from 63 preterm placentas among 151 specimens, which were delivered at <32 wk of gestation. Of the 63 placentas, 52 (83%) revealed CAM in cultures positive for Ureaplasma spp., however, CAM was observed only in 30% (26/88) of cultures negative for Ureaplasma spp. (p < 0.01). Colonization by Ureaplasma spp. was an independent risk factor for CAM (OR, 11.27; 95% CI, 5.09-24.98). Characteristic neutrophil infiltration was observed in the amnion and subchorion (bistratified pattern) in cultures positive for Ureaplasma spp. FISH analysis of CAM placenta with male infant pregnancy indicated that bistratified infiltrated neutrophils showed the XX karyotype and umbilical vein infiltrated neutrophils showed XY karyotype. The distribution of sulfoglycolipid, the receptor of Ureaplasma spp., was mainly detected in the amnion. Ureaplasmal urease D protein and ureB gene were both detected in the amnion, indicating direct colonization by Ureaplasma spp.