NEONATAL AIRWAY COLONIZATION WITH GRAM-NEGATIVE BACILLI - ASSOCIATIONWITH SEVERITY OF BRONCHOPULMONARY DYSPLASIA

Background. Airway colonization with Gram-negative bacilli (GNB) and G ram-positive cocci (GPC) is common in mechanically ventilated neonates . Whether GNB are related to nosocomial bloodstream infection (BSI) an d/or to the severity of bronchopulmonary dysplasia (BPD) is unknown. M ethods. We prospectively examine this relationship using a cohort desi gn. Data from 260 less than or equal to 1250-g birth weight inborn inf ants (1991 to 1995) intubated greater than or equal to 2 weeks include d 917 serial tracheal cultures and 583 blood cultures. The severity of BPD was assessed by duration of mechanical ventilation, oxygen depend ency at 36 weeks of postconceptional age and the use of home oxygen su pplementation. Results. After 2 weeks of ventilation, 80% of the infan ts were colonized with GPC (Staphylococcus epidermidis and Staphylococ cus haemolyticus in 90% of the cases). Superimposed on 36% of these in fants was GNB airway colonization with Klebsiella pneumoniae (25%), En terobacter cloacae (25%), Escherichia coli (25%), Pseudomonas aerugino sa (10%), Serratia marcescens (10%), Acinetobacter baumannii and Haemo philus influenzae (5%), Comparison between 174 GPC- and 86 GNB-coloniz ed infants showed that demographics, birth weight, gestational age, pe rinatal risk factors and mortality were similar. Fifteen percent of GN B-colonized infants developed BSI caused by GNB and 14% developed BSI caused by GPC. No significant temporal relationship between airway col onization and BSI was noted. GNB infants were ventilated longer and re quired oxygen at 36 weeks of postconceptional age and home oxygen supp lementation twice as often as infants colonized only with GPC. GNB col onization was a predictor of severe BPD after controlling for ventilat ion. Ureaplasma colonization occurred in 28% of GNB-colonized and 33% of noncolonized infants and was not a predictor of BPD severity. Concl usion. GNB airway colonization creates a moderate risk far BSI. Antibi otic treatment does not regularly eradicate GNB. GNB airway colonizati on is associated with severe BPD, but further studies will be necessar y before therapeutic efforts to eradicate GNB from the airways should be undertaken.