Pulmonary Ureaplasma urealyticum is associated with the development of acute lung inflammation and chronic lung disease in preterm infants.

Previously, we have reported marked pulmonary inflammation in infants who develop chronic lung disease of prematurity. We revisited these infants who did not have clinical or laboratory evidence of infection and searched for Ureaplasma urealyticum, group B streptococci, and other microbes by reverse transcription-PCR performed on RNA extracted from 93 bronchoalveolar lavage samples. From infants ventilated for respiratory distress syndrome, 6 (gestation, 28 wk; birthweight, 880 g) were positive for U. urealyticum and 11 (25 wk, 800 g) were negative. Five (83%) positive and four (36%) negative infants developed chronic lung disease. Each infant was colonized with either biovar 1 or biovar 2 but not both. U. urealyticum was very weakly detectable in two infants on d 1 but was detected in five of six infants at d 10. Furthermore, pulmonary neutrophils, alveolar macrophages, soluble intercellular adhesion molecule-1, and IL-1beta on d 10 and IL-6 and IL-8 at d 1 were significantly increased in the positive group. A variety of organisms were identified in six samples between 14 and 21 d of age, but all samples were negative for group B streptococci. Our data suggest that U. urealyticum colonization is associated with the development of pulmonary inflammation in infants who subsequently develop chronic lung disease.