Gram-negative bacilli associated with catheter-associated and non-catheter-associated bloodstream infections and hand carriage by healthcare workers in neonatal intensive care units.

OBJECTIVE: Bloodstream infections caused by Gram-negative bacilli are a substantial cause of morbidity and mortality in infants in neonatal intensive care units. This study describes the species of Gram-negative bacilli causing bloodstream infections in two neonatal intensive care units, compares characteristics of catheter-related and non-catheter-related bloodstream infections, and compares species and antibiotic resistance patterns of these organisms with those isolated from the hands of nurses working in the same neonatal intensive care units.
DESIGN: Interventional study.
SETTING: Two high-risk neonatal intensive care units. PATIENTS: Neonates hospitalized for >or =24 hrs.
INTERVENTIONS: Prospective surveillance for bloodstream infections was performed in two neonatal intensive care units from March 2001 to January 2003. Hand cultures were obtained quarterly from participating nurses immediately after they performed hand hygiene.
MEASUREMENTS AND MAIN RESULTS: There were 298 episodes of bloodstream infections among 2,935 admissions (5.75 episodes per 1,000 patient-days); 77 of 298 (26%) episodes were caused by Gram-negative bacilli. Among these, 47 (61.0%) were catheter-related bloodstream infections (2.61 episodes per 1,000 catheter-days). Eleven and 24 Gram-negative bacilli species were isolated from neonates and nurses, respectively. The most common Gram-negative bacilli causing bloodstream infections were Klebsiella pneumoniae (38.7%), Escherichia coli (21.2%), Enterobacter cloacae (11.2%), and Serratia marcescens (11.2%). In contrast, Acinetobacter lwoffi (18.1%), K. pneumoniae (11.7%), E. cloacae (10.6%), K. oxytoca (10.6%), and Pseudomonas spp. (7.4%) were most commonly isolated from hands of nurses. E. coli, P. aeruginosa, E. cloacae, and E. aerogenes were significantly more likely to cause bloodstream infections than to be isolated from nurses' hands (all p < .001). Although 39% of bloodstream infections were non-catheter-related, there were no significant differences in types of organisms or antimicrobial resistance patterns between catheter-related bloodstream infections and non-catheter-related bloodstream infections (all p > or = .35). Resistance patterns were similar between Gram-negative bacilli isolates from neonates and nurses' hands except for a significantly higher proportion of resistance to cefotaxime and gentamicin among neonatal isolates of K. pneumoniae (p < .05).
CONCLUSIONS: Gram-negative bacilli species isolated from neonatal bloodstream infections and nurses' hands varied significantly. Clean hands of providers are an unlikely source of endemic Gram-negative bacilli, suggesting that prevention strategies should focus more on control of endogenous neonatal flora or environmental sources.