Identification and quantification of ureaplasmas colonizing the respiratory tract and assessment of their role in the development of chronic lung disease in preterm infants

Background. The role of Ureaplasma urealyticum in the development of chronic lung disease (CLD) in preterm infants continues to be disputed. Recently U. urealyticum has been found to consist of two species, U. urealyticum and Ureaplasma parvum, a finding that has not been considered in previous studies of CLD. This study examined the possible relationships between development of CLD and respiratory colonization by these newly redefined species, their concentrations in lower respiratory secretions and the effect of pulmonary surfactant treatment on these relationships in preterm infants with birth weights < 1500 g. Methods. Endotracheal aspirates (ETA) were collected from intubated infants when airway suctioning was medically required. ETA were stored at -80 degreesC until quantitative cultures for ureaplasmas and Mycoplasma hominis were performed. Culture results were correlated with development of CLD. Results. Of 475 infants (birth weights < 1500 g) admitted during the 2-year study period, 272 were excluded because they were not intubated or were extubated before ETA could be obtained. An additional 28 infants died, were discharged or were transferred before they could be assessed for CLD. From the remaining 175 infants ureaplasmas were isolated from 66 (38%). No statistically significant associations were identified between development of CLD and the Ureaplasma species isolated, or concentration of ureaplasmas in lower respiratory secretions. These findings were not altered by treatment with pulmonary surfactant (Survanta). Conclusion. Lower respiratory colonization by ureaplasmas does not appear to be a contributory cause of CLD in preterm infants.