Objectives Ureaplasma species were associated bronchopulmonary dysplasia in preterm infants. We aim to analyze the antibiotic susceptibility of ureaplasma urealyticum and clinical manifestations in preterm infants with ureaplasma urealyticum colonization.

Methods In a retrospective study, 416 preterm infants (≤ gestation 32 wk) and their mothers admitted to Severance Children’s Hospital and Gangnam Severance Hospital NICU between Jan 2008. to Jun 2011, were reviewed. Ureaplasma test was done by culture for mothers and PCR in urine and tracheal aspirates for preterm infants. Ureaplasma colonization was confirmed 7.5% of infants, and 31% of the mothers. If positive result was noted, all infants were initially treated with erythromycin empirically.

Results Thirty one infants who had positive ureaplasma PCR test (28.3±3.1wk, 1050±490g) and 385 infants with negative test (29.0±3.2 wk, 1190±550g) were recruited as controls. Infants with ureaplasma infection had longer durations of oxygen administration (p=0.039) and mechanical ventilation (p=0.041). The incidence of pathologic chorioamnionitis were significantly higher (p<0.001). Infants with ureaplasma infection had higher incidence of moderate/severe BPD. For antimicrobial susceptibility, 23% of erythromycin resistance, 16% of zithromycin resistance, 38% of ciprofloxacin resistance and no jasamycin resistance were shown. Among 31 infants with erythromycin treatment, 18 (58%) of susceptible, 6 (19%) of intermediate were cured after 13 days of treatment, and 4 showed poor response erythromycin treatment, 2 changed to josamycin and 2 infants to clarithromycin and all were completely treated.

Conclusion Ureaplasma colonized infants showed higher incidence of BPD. Proper antimicrobial use may reduce the morbidity associated with ureaplasma colonization.