Prevalence, perinatal risk factors and clinical outcomes of respiratory Ureaplasma species colonization in hospitalized preterm infants

Objective To investigate the prevalence, perinatal risk factors, and clinical outcomes associated with Ureaplasma species ( Ureaplasma spp.) colonization in hospitalized preterm infants. Methods This retrospective study included preterm infants (37 weeks’ gestation) admitted to the Neonatology Department of the Children's Hospital of Soochow University, China, between December 2023 and June 2025. Infants transferred within 72 h of birth and tested for Ureaplasma spp. in nasopharyngeal aspirates within 72 h were eligible. Infants with delayed testing, incomplete clinical data, or early death or discharge were excluded. Nasopharyngeal aspirates samples were analyzed for Ureaplasma spp. DNA by polymerase chain reaction. Demographic, perinatal, laboratory, and clinical outcome data were collected. Comparisons between Ureaplasma spp.-positive and Ureaplasma spp.-negative groups were performed, and multivariate logistic regression was used to evaluate the association between Ureaplasma spp. colonization and major morbidities. Results Among 368 eligible preterm infants, 58 (15.8%) were Ureaplasma spp.-positive. The colonization rate increased progressively with decreasing gestational age (GA), reaching 31.8% among infants 28 weeks, and was highest among those with a birth weight of 1,000–1,499 g (20.4%). Ureaplasma spp.-positive infants had a significantly lower GA ( P 0.05). Vaginal delivery and prolonged rupture of membranes (PROM) were more common in the Ureaplasma spp.-positive group (both P 0.001), whereas gestational hypertension was more frequent in the negative group ( P = 0.008). The positive group had higher white blood cell counts and a greater frequency of elevated C-reactive protein (CRP) levels ( P 0.05). Clinically, Ureaplasma spp. colonization was associated with more frequent and prolonged oxygen supplementation and higher incidences of bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), sepsis, and retinopathy of prematurity (ROP) (all P 0.05). After adjusting for confounders, Ureaplasma spp. colonization remained independently associated with BPD, NEC, and ROP ( P 0.05), but not with sepsis. Conclusions Ureaplasma spp. colonization is common in hospitalized preterm infants, particularly among those of lower gestational age. Vaginal delivery and PROM are significant perinatal risk factors. Ureaplasma spp. colonization is associated with heightened inflammatory responses and independently contributes to major morbidities, including BPD, NEC, and ROP, but not with sepsis after adjustment for confounders.