Ureaplasma urealyticum as a cause of pneumonia in preterm infants: analysis of the white cell response.

The tracheal isolation of Ureaplasma urealyticum from critically ill infants was investigated to determine if the organism was associated with an inflammatory response. Twenty nine neonates consecutively admitted for acute respiratory disease, with birthweights of < 1301 g and no evidence of viral, chlamydial, or bacterial infections, were identified. Culture results for ureaplasmas were correlated with white cell counts and clinical and radiographic features. Sixteen infants had tracheal aspirates and/or blood specimens positive for U urealyticum. Pneumonia was diagnosed more frequently in the U urealyticum positive infants than in the 13 who were negative for the organism. The mean total white cell count, absolute neutrophil, and band form counts were significantly higher in the U urealyticum positive group than in the negative group. These data suggest that U urealyticum can induce an inflammatory response in selected individuals who present with clinical, radiographic, and, in some instances, histological features of pneumonia.