Patterns of colonization with Ureaplasma urealyticum during neonatal intensive care unit hospitalizations of very low birth weight infants and the development of chronic lung disease.

BACKGROUND: Ureaplasma urealyticum and its association with chronic lung disease (CLD) of prematurity has remained a controversial topic. To readdress this question, we performed a longitudinal study using culture and polymerase chain reaction to detect U urealyticum in the respiratory tract of very low birthweight infants throughout their neonatal intensive care unit hospitalizations. METHODS: We screened 125 infants weighing <1500 g and/or <32 weeks' gestational age over a 12-month period, collecting endotracheal, nasopharyngeal, and throat specimens on days of age 1, 3, 7, and weekly thereafter. CLD was defined as dependency on supplemental oxygen at 28 days and at 36 weeks' postconceptional age. RESULTS: Forty infants (32%) had 1 or more positive specimens by culture or polymerase chain reaction. We identified 3 patterns of U urealyticum colonization: persistently positive (n = 18), early transient (n = 14), and late acquisition (n = 8). We compared the rates of CLD in each of the 3 colonized groups with the rate of CLD in the noncolonized group. We found a significantly higher rate of CLD at 28 days of age (odds ratio: 8.7; 95% confidence interval: 3.3, 23) and at 36 weeks' postconception (odds ratio: 38.5, 95% confidence interval: 4.0, 374) only for infants with persistently positive colonization. CONCLUSIONS: This study demonstrates that the risk of developing CLD varies with the pattern of U urealyticum colonization. Only the persistently positive colonization pattern, which accounted for 45% of the U urealyticum-positive infants, was associated with a significantly increased risk of development of CLD.