[Clinical characteristics of ureaplasma urealyticum pneumonia in preterm infants with gestational age less than 32 weeks].

Objective: To investigate the clinical characteristics of ureaplasma urealyticum(UU) pneumonia in preterm infants less than 32 weeks. Methods: Preterm infants with gestational age <32 weeks who were hospitalized in neonatal intensive care unit (NICU) of Peking University Third Hospital from January 2018 to December 2019 were retrospectively analyzed. There were 105 premature infants, 63 males and 42 females. After the first diagnosis of pneumonia during hospitalization, the airway secretions were collected for UU nucleic acid detection. They were divided into UU positive group and UU negative group. Perinatal factors, comorbidities, antibiotic treatment and clinical outcomes were compared between the two groups. SPSS24.0 statistical software was used for statistical analysis. T test or chi-square test was used to compare the two groups, and logistic regression was used for multivariate analysis. Results: Among 105 cases of preterm pneumonia, 37 cases (35.2%) were diagnosed with UU pneumonia and 68 cases (64.8%) were negative for UU test. There was no significant difference in gestational age [28(27,30) weeks vs 29(28,30)weeks,Z=-0.98, P>0.05] and birth weight[(1 282.03±292.49)g vs (1 196.62±322.89)g,t=1.34, P>0.05] between the two groups. In UU pneumonia group, the rate of singleton (86.5% vs 50%,χ2=12.15), chorioamnionitis (10.8% vs 1.55%,χ2=4.61), premature rupture of membranes>12 h (32.4% vs 11.8%,χ2=5.37) and vaginal delivery rate(59.5% vs 35.3%,χ2=4.75) were higher than UU negative group (P<0.05). Further multivariate logistic regression analysis showed that vaginal delivery was an independent risk factor for UU (OR = 2.694, 95%CI: 1.113-6.525). WBC count in UU positive group was significantly higher [12.85×109/L (9.32×109/L,17.22×109/L) vs 9.06×109/L (7.06×109/L,13.37×109/L), Z=-3.01, P<0.05], and oxygen consumption time was prolonged[ (46.8±19.8)d vs (37.8±20.7)d, t=2.177,P<0.05]. The incidence of hemodynamically significant patent ductus arteriosus (29.7% vs 57.4%,χ2=6.265) and respiratory distress syndrome (54.1% vs 75.0%,χ2=4.801) in UU positive group was significantly lower than that in UU negative group (P<0.05). There was no significant difference in bacterial infection(62.2% vs 50.0%, χ2=8.826) and antibiotic(48.6% vs 47.1%,χ2=1.352) between the two groups(all P>0.05). After azithromycin treatment, the time for UU negative was (9.00±3.14) days. There was no significant difference in the incidence of bronchopulmonary dysplasia(73.0% vs 69.1%,χ2=0.036), retinopathy of prematurity(10.8% vs 26.5%,χ2=2.665), neonatal necrotizing enterocolitis(2.7% vs 1.5%,χ2=0.195), intraventricular periventricular hemorrhage (69.4% vs 72.1%,χ2=0.003) and periventricular leukomalacia (8.1% vs 8.8%,χ2=0.016) between the two groups (P>0.05). Conclusions: If premature rupture of membranes >12 h, combined with chorioamnionitis, and vaginal delivery, preterm infants less than 32 weeks are likely to have an increased risk of UU infection. UU pneumonia in preterm infants less than 32 weeks old was characterized by prolonged oxygen consumption and increased white blood cell count. Oral azithromycin treatment could effectively remove UU and improve prognosis.