Aim To ascertain the incidence of respiratory tract colonization in extremely low gestational age newborns (ELGANs) with Ureaplasma parvum and Ureaplasma urealyticum and determine if there is a difference in the severity of bronchopulmonary dysplasia (BPD) between ELGANs with and without Ureaplasma species (spp) colonization. Methods We reviewed the medical records of ELGANs 23 0/7–27 6/7 weeks of gestation, tested for U. parvum and U. urealyticum in our Center from January 1, 2009 to December 31, 2019. Ureaplasma spp were identified with the Mycofast Screening Revolution assay based on liquid broth cultures or with polymerase chain reaction. Results This study enrolled 196 preterm newborns. Fifty (25.5%) newborns had Ureaplasma spp respiratory tract colonization, with U. parvum being the predominant species. The incidence rate of respiratory tract colonization with Ureaplasma spp slightly increased in the studied period. The incidence rate for 2019 was 16.2 per 100 infants. BPD severity significantly correlated with Ureaplasma spp colonization ( P = 0.041). After controlling for other risk factors for BPD in a regression model, preterm infants colonized with Ureaplasma spp had 4.32 times (95% confidence interval, CI 1.20-15.49) higher odds for developing moderate-to-severe BPD. Conclusions U. parvum and U. urealyticum could be associated with the development of BPD in ELGANs.

Purpose. With this 11-year long retrospective study (2009–2019) we wanted to ascertain the incidence of respiratory tract colonisation of extremely low gestational age newborns (ELGANs) with Ureaplasma parvum and Ureaplasma urealyticum and if there is a difference in the severity of bronchopulmonary dysplasia (BPD) between preterm infants with proven respiratory tract colonisation with U. parvum and U. urealyticum and without colonisation, controlled for other risk factors for BPD. Methods. We reviewed the medical records of ELGANs 23 0/7–27 6/7 weeks of gestation, tested for U. parvum and U. urealyticum. The causative Ureaplasma species (spp.) were identified using Mycofast Screening Revolution assay based on liquid broth cultures or with the PCR method. Results. This study included 196 preterm newborns. Fifty (25.5%) newborns had Ureaplasma spp. respiratory tract colonisation, with U. parvum being the predominant species. The results showed a slightly growing incidence rate of respiratory tract colonisation with Ureaplasma spp. in the observed period. The incidence rate for 2019 was 16.2 per 100 infants. We also discovered a statistically significant correlation between the severity of BPD and the colonisation with Ureaplasma spp. (p=0.041). Controlling for other risk factors for BPD in the regression model, the preterm infants colonised with Ureaplasma spp. had 4.32-times (95% confidence interval, CI 1.20–15.49) higher odds for developing moderate to severe BPD. Conclusions. Our results suggest that U. parvum and U. urealyticum could be associated with the development of BPD in ELGANs.