Incidence, Risk Factors, Short-term Outcomes, and Microbiome of Ventilator-associated Pneumonia in Very-low-birth-weight Infants: Experience at a Single Level III Neonatal Intensive Care Unit

Abstract

Background: Ventilator-associated pneumonia (VAP) is a common hospital-acquired infection in neonates on invasive mechanical ventilation, resulting in high morbidity and mortality. The objective of this study is to determine the incidence, risk factors, short-term outcomes and microbiome associated with VAP in very-low-birth-weight (VLBW) infants born at <32 weeks of gestational age (GA). Methods: Retrospective study of intubated VLBW infants born at <32 weeks of GA admitted to the Los Angeles General Medical Center neonatal intensive care unit from July 2015 to July 2021 who had routine tracheal aspirate cultures obtained. Neonates were retrospectively classified into 3 groups, confirmed VAP, suspected VAP and no VAP, for comparison of risk factors, outcomes and airway microbial colonization. Results: Eighty-seven infants met inclusion criteria with a mean GA of 26.1 ± 1 weeks and mean birth weight of 812 ± 281 g. The incidence of VAP was 7.8 per 1000 ventilator days, and the most common causative organisms were Gram-positive organisms (39%), predominantly coagulase-negative Staphylococcus. Duration of postnatal dexamethasone exposure predicted VAP compared to no VAP (coefficient, 0.31; 95% CI 0.03–0.59; P = 0.03) after adjusting for duration of intubation, surfactant use and antenatal steroid exposure. Infants with VAP had higher rate of grade 2/3 bronchopulmonary dysplasia (P = 0.03) and longer hospital stay (P = 0.04). Conclusions: VAP occurs at a high rate in VLBW infants who are exposed to prolonged dexamethasone use. It is predominantly caused by Gram-positive organisms.