Rates and Pathogen Profile of Device-Associated Infections among Neonatal Intensive Care Unit Patients: Data from the National Healthcare Safety Network, 2006-2008

Background:

Neonatal intensive care unit (NICU) patients are at risk for healthcare-associated infections (HAIs) due to their high exposure to invasive devices and immature immune systems. Understanding the epidemiology of HAIs in this population is a key step in the development of targeted prevention strategies.

Objective:

To describe rates and pathogen distribution of device-associated infections (DAIs) in NICU patients, and compare differences in infection rates by hospital type (children's vs. general hospitals).

Methods:

We analyzed central-line associated bloodstream infections (CLABSI), umbilical catheter-associated BSI (UCAB), and ventilator associated-pneumonia (VAP) reported by 304 NICUs participating in the National Healthcare Safety Network (NHSN) from 2006-2008. BSI and VAP were defined using standard NHSN criteria. Data were pooled by birthweight (BW) category for each NICU within children's and general hospitals. Differences in pooled mean incidence rates were examined using Poisson regression; non-parametric tests for comparing median and rate distributions were used. Pathogen distribution by BW category was determined.  P values reported represent Poisson regression results. Rates are reported per 1,000 device-days.

Results:

There were a total of 1,088 CLABSI, 531 UCAB, and 591 VAP reported. Pooled mean rates by BW category, (≤ 750g, 751-1000g, 1001g-1500g, 1501g-2500g, > 2500g, respectively) were:  3.94, 3.09, 2.25, 1.90, 1.60 for CLABSI; 4.52, 2.77, 1.70, 0.91, 0.92 for UCAB; and 2.36, 2.08, 1.28, 0.86, 0.72 for VAP. NICU CLABSI and UCAB incidence rates did not differ between children's and general hospitals regardless of BW category. Pooled mean NICU VAP rates were lower in children's compared to general hospitals among neonates weighing ≤ 750g (1.68 vs. 2.68, P<0.001) or 751-1000g (1.10 vs. 2.31, P=0.01), but similar for other BW categories (Table).  The most frequently reported pathogens for BSI were coagulase-negative staphylococci (28%), Staphylococcus aureus (19%), Candida sp. (13%), and Enterococcus sp. (12%). VAP pathogen distribution was as follows: Pseudomonas sp. (16%), S aureus (15%), Klebsiella sp. (14%), and Enterobacter sp. (10%). Pathogen frequencies did not vary significantly by BW category or hospital type. Of the 673 S. aureus isolates with susceptibility results reported, 33% were methicillin-resistant.

Conclusions:

Neonates ≤ 750 g had the highest incidence of each reported DAI. Adjusting for BW category, pooled mean NICU incidence rates did not differ between children's and general hospitals, with the exception of VAP. Variations in the application of diagnostic criteria for pneumonia may explain some of the differences in VAP rates. Pathogens associated with these infections can pose treatment challenges; continued efforts at prevention need to be applied to all NICU settings.