AIRWAY COLONIZATION WITH GRAM NEGATIVE BACILLI (GNB): ASSOCIATION WITH SEVERITY OF BRONCHOPULMONARY DYSPLASIA (BPD). † 1550

Abstract

Airway colonization with GNB and gram-positive cocci (GPC) is common in mechanically ventilated neonates. Whether it is causally related to nosocomial infections (NOS) and/or to the severity of BPD is unclear. We examine these relationships using a cohort design. Data from 260≤ 1250 g Bwgt. in-born infants (1991-95) who were intubated >2w included 917 serial tracheal cultures (TC) and 583 blood cultures. BPD severity was assessed by duration of mechanical ventilation (VENT), O2 dependency at 36 weeks of conceptional age(CA36) and by the need for home O2 supplementation (HOM). Variables equally distributed among subgroups and not related to BPD were: male (50%), black(24%), C/S (62%), Ureaplasma colonization (33%), surfactant (88%) and dexamethasone Tx (72%). After 2 w of VENT 95% of infants were colonized with GPC (S epidermidis and haemolyticus 90%).Superimposed on 30% of these infants was GNB airway colonization with Klebsiella (25%), Enterobacter (25%), E. coli (25%), Pseudomonas (10%), Serratia (10%), Acinetobacter and H. influenza (5%). Except for Serratia, all GNB were endemic. Comparisons between 174 GPC and 86 GNB infants were made. Demographics, Bwgt, GA, and perinatal risk factors were similar. GNB infants had longer LOS and VENT, also required O2 at CA36 and HOM more than GPC patients (*P<0.01). GNB is a predictor of severe BPD after controlling for VENT (logistic reg). About 25% of GPC colonized infants developed NOS (only 1/3 of which were temporally related). Ten% GNB colonized infants had GPC and GNB sepsis. All GNB NOS and 90% GNB colonized newborns were treated and survived. TC remained GNB positive in 70%. Conclusion: Airway colonization with GNB is a moderate risk for nosocomial infection. Antibiotic Tx does not regularly erradicate GNB, but may decrease neonatal mortality. Persistent GNB airway colonization is significantly associated with severe BPD.Table