Evidence of an immune response to Ureaplasma urealyticum in perinatal morbidity and mortality

Ureaplasma urealyticum has been associated with spontaneous pregnancy loss, neonates requiring intensive care, neonatal death and more recently respiratory disease. Due to high colonization rates it has been difficult to determine whether Ureaplasmas cause infection in humans. Therefore in this overview sera from over 300 cases were assessed to determine the prevalence of an elevated antibody response to U. urealyticum. Prospectively 22 cases of stillbirth, 75 neonatal deaths and 46 normal cases were studied, in addition to 259 retrospective cases of neonates with respiratory disease of which 56 were term gestations. An antibody response greater than or equal to 1:32 to at least 1 of the 8 serovars of U. urealyticum occurred in 77.3% of stillbirths, 58.3% of respiratory disease cases, 69.3% of neonatal deaths and 80.4% of term neonates, compared to 6.5% of well term neonates (P less than 0.001 each). Elevated titers were detected in the mothers in 65.0, 54.7, 62.9, and 64.5% of each group, respectively, compared to 8.5% in mothers of healthy control cases (P less than 0.001 each). When all groups were combined the mortality rate was 61.3% among the 155 neonates who had at least one Ureaplasma titer of greater than or equal to 1:32 compared to 27.1% of 168 with a maximum titer of 1:16 (P less than 0.001). Thus in humans the prevalence of antibody response to any of 8 U. urealyticum serovars was significantly higher in potentially infected cases such as stillbirth and neonatal respiratory disease, particularly among those born at term or who die, compared to normal mothers and neonates. Presence of an elevated antibody response correlated significantly with an increased mortality rate.