Our hypothesis is that treatment of known Ureaplasma spp. infection of the airways in very low birth weight (VLBW) infants with azithromycin will eradicate the organisms and lessen the proinflammatory state caused by infection that puts them at risk for Bronchopulmonary Dysplasia (BPD). We propose to conduct a randomized trial of early (less than 3 days of age) treatment with intravenous azithromycin versus expectant management for VLBW infants with Ureaplasma spp. respiratory tract infection with the following specific aims: (1) Determine microbiological efficacy, pharmacokinetics, and safety of azithromycin treatment for eradication of Ureaplasma spp. in preterm infants, (2) Determine the respiratory outcomes of infants in the two treatment groups and those without respiratory tract Ureaplasma spp. infection