Lung Pathology in Premature Infants with Ureaplasma urealyticum Infection

Abstract

Respiratory tract colonization with Ureaplasma urealyticum in preterm infants has been associated with a higher incidence of pneumonia, severe respiratory failure, bronchopulmonary dysplasia (BPD), and death. In this report, we characterize the lung pathology and expression of tumor necrosis factor-alpha (TNF-alpha) associated with U. urealyticum pneumonia in very low-birth weight infants (VLBW; < or =1500 g). Lung pathology of archived autopsy specimens was retrospectively reviewed in three groups of VLBW infants: 5 gestational controls who died from nonpulmonary causes, 13 infants with pneumonia who were culture and/or PCR negative for U. urealyticum, and 5 infants with pulmonary disease and positive for U. urealyticum by tracheal aspirate and/or lung tissue culture or polymerase chain reaction (PCR). Presence and extent of alveolar macrophages and neutrophils, as well as interstitial lymphocytic infiltration and fibrosis were evaluated. PCR was performed on formalin-fixed, paraffin-embedded lung sections. Additional sections were immunostained for TNF-alpha. The peripheral total white blood cell counts and absolute neutrophil counts were three-fold higher in infants with U. urealyticum pneumonia than cell counts in infants infected with other organisms. There was a trend toward a predominance of neutrophils in alveoli of non- Ureaplasma pneumonia infants, but a trend toward a predominance of alveolar macrophages in U. urealyticum-infected infants. The most striking finding was the presence of increased interstitial fibrosis in all Ureaplasma-infected infants. TNF-alpha immunoreactive cell density was very low in the gestational controls, but increased in both pneumonia groups. We conclude that persistent lung U. urealyticum infection may contribute to chronic inflammation and early fibrosis in the preterm lung.

Role of Ureaplasma Respiratory Tract Colonization in Bronchopulmonary Dysplasia Pathogenesis

“…54 These changes in elastin and smooth muscle are similar to those reported for infants with BPD and those dying with Ureaplasma infection. 49,50,58 Overall, the sheep studies lend support to the clinical observation of less respiratory distress syndrome but more BPD after Ureaplasma exposure.…”

“…42, 48 In archived autopsy specimens of colonized infants, we observed early lung fibrosis, increased number of myofibroblasts, disordered elastin accumulation, and increased number of immunoreactive cells expressing inflammatory mediators tumor necrosis factor-alpha (TNFα) and transforming growth factor β1 (TGFβ1). 49, 50 …”

Disordered Pulmonary Myofibroblast Distribution and Elastin Expression in Preterm Infants with Ureaplasma Urealyticum Pneumonitis

“…in a review of lung pathology of archived autopsy specimens from Ureaplasmainfected preterm infants, we observed moderate to severe fibrosis in all Ureaplasma-'miQcitd infants compared to gestational controls and infants who died with pneumonia from other causes [8].…”

“…and 5 infants with pulmonary disease and positive for U urealyticum by tracheal aspirate or lung tissue culture or PCR. Clinical and laboratory data of the groups of infants are presented in the previous report [8]. All infants died at 45 d of age or earlier.…”

Infection with Ureaplasma urealyticum: is there a specific clinical and radiological course in the preterm infant?

“…4 The genital mycoplasmas, in particular Ureaplasma urealyticum, are the most commonly isolated organisms in the genital tract of mothers. 5 U urealyticum has been shown to cause chronic inflammation and early fibrosis in the preterm lung, 6 and has been associated with the development of CLD. 7 8 Our policy has been to culture all ventilated infants below 30 weeks gestation for the genital mycoplasmas.…”