Abstract and Introduction
Abstract
Background: Gram-negative bloodstream infections (BSIs) cause 20-30% of late onset sepsis in neonatal intensive care unit (NICU) patients and have mortality rates of 30-50%. We investigated risk factors for late onset Gram-negative sepsis in very low birth weight (<1500 g) NICU patients.
Methods: We performed a case-control study as part of a larger 2-year clinical trial that examined the effects of hand hygiene practices on hospital-acquired infections. In this substudy, a case was a very low birth weight infant with a hospital-acquired Gram-negative BSI; control subjects, matched on study site and hand hygiene product, were chosen randomly from the patients who did not have Gram-negative BSIs. Potential risk factors were analyzed by Mantel-Haenszel methods and conditional logistic regression.
Results: There were 48 cases of Gram-negative BSI. In multivariate analysis, we found that the following variables were significantly associated with Gram-negative BSI: central venous catheterization duration of >10 days; nasal cannula continuous positive airway pressure use; H2 blocker/proton pump inhibitor use; and gastrointestinal tract pathology.
Conclusions: These analyses provide insights into potential strategies to reduce Gram-negative BSIs. Catheters should be removed as possible and H2 blockers/proton pump inhibitors should be used judiciously in NICU patients. The association between nasal cannula continuous positive airway pressure and Gram-negative BSIs requires further investigation. The association of gastrointestinal tract pathology with Gram-negative BSIs identifies a high risk group of neonates who may benefit from enhanced preventative strategies.
Introduction
Preterm birth rates are rising, making complications of low birth weight a significant public health problem. In the United States, 12% of all births are premature, an increase of 12% since 1990 and 27% since 1981. The most common nosocomial infections in neonatal intensive care units (NICUs) are bloodstream infections (BSIs), and infants hospitalized in NICUs have higher BSI rates than any other pediatric or adult population. Late onset sepsis, defined as 1 or more positive blood cultures obtained after 72 hours of life, occurs in ~25% of very low birth weight (VLBW) infants (<1500 g). The most common cause of BSIs remains Gram-positive skin flora; thus prevention efforts have largely focused on these infections. However, recent reports describe increasing rates of Gram-negative BSIs among infants hospitalized in NICUs as well as higher mortality (40%) when compared with those caused by Gram-positive organisms (25%). Overall Gram-negative bacilli cause 20-30% of episodes of late onset sepsis and 30% of pneumonias in NICU patients. Despite their increasing incidence and high mortality, risk factors for Gram-negative BSIs have not been well-defined and can differ from those described for Gram-positive bacteria and Candidaspp. We used recently collected data from a clinical trial to assess risk factors for Gram-negative BSIs in VLBW infants hospitalized in the NICU.