[Characteristics of airway colonization in mechanically ventilated newborn infants]

This study was designed to define the pattern of airway colonization in mechanically ventilated neonates and to assess whether this is associated with clinical signs of infection and/or local or systemic inflammation. One hundred and fifty-seven bronchoalveolar lavages (BAL) were obtained from 40 intubated neonates for microbiologic and cytologic evaluation of the distal airway. Concomitantly with each BAL, clinical data and laboratory tests were recorded. Ninety-seven BAL were negative, whilst 56 (37%) yielded the growth of gram-positive bacteria (84%), gram-negative bacteria (6%), fungi (5%), or P. carinii (5%). Airway colonization occurred in 9 (22%) neonates within the first 72 hours of life and in 31 (78%) during the following days. S. aureus was the most commonly isolated organism (70%). Clinical signs of pulmonary infection were present in all cases of vertical colonization and in 35 (66%) of nosocomial transmission. Blood and BAL white cell counts were higher coincidentally with airway colonization (p = 0.13 and p = 0.57, respectively). Antibiotic treatment was changed on the basis of BAL culture results. Follow-up cultures of the BAL were obtained in 13 neonates in whom antibiotics were changed. Negative cultures were found in 8 of these neonates, and 50% of these cases showed clinical improvement. Further work is needed to assess the cost-benefit ratio of prophylactic antibiotic administration in intubated neonates and the possible advantage(s) of treating microorganisms colonizing the airway of these subjects.