Central Line-Associated Bloodstream Infections in Hematopoietic Stem Cell Transplant and Hematology/Oncology Units: Incidence and Pathogens

Background: Central line-associated bloodstream infections (CLABSIs) are important causes of morbidity and mortality in hematology/oncology (HONC) and hematopoietic stem cell transplant (BMT) patients. Although gram-negative bacteria have historically been major causes of BSI in neutropenic cancer patients, studies have shown increases in the prevalence of gram-positive organisms in recent decades.
Objective: To determine CLABSI incidence rates and pathogen distribution in BMT and HONC units reporting to the National Healthcare Safety Network (NHSN) from 2006-2008.

Methods: NHSN BMT and HONC units are locations where ≥80% of patients are receiving care related to a BMT or hematological/oncological disease. Pooled mean incidence rates in patients with permanent (tunneled/implanted) and temporary (non-tunneled) central lines and device utilization ratios (DURs) were calculated. Pathogen distribution was determined using event data from facilities where unit-month denominator data were not missing.

Results: Of 778 total CLABSIs, 335 (43%) were from BMT, 298 (38%) from adult HONC, and 145 (19%) from pediatric HONC units. Of these, 728 CLABSIs from 950 unit-months of surveillance were included in incidence rate calculations. Permanent line utilization was higher than temporary line utilization. Pooled mean incidence rates were higher in HONC patients with temporary lines than in those with permanent lines (Table). The most common pathogens on BMT units were coagulase-negative staphylococci (CNS) (19%), Escherichia coli (15%) and Enterococcus faecium (12%); on adult HONC units, CNS (20%), Staphylococcus aureus (14%) and E. coli (11%); and on pediatric HONC units, CNS (25%), E. faecium (9%), Pseudomonas aeruginosa and E. coli (each 7%). Vancomycin resistance was reported in 74/95 E. faecium isolates with available susceptibility data (78%), making vancomycin-resistant E. faecium (VRE) the fourth most common pathogen overall (9% of all CLABSIs).

Conclusions: CLABSI incidence rates were high in BMT and HONC units when compared to published NHSN ICU CLABSI incidence rates (≤ 2.5/1000 central line days in 75% of ICU types). Our results support other study findings of increased prevalence of gram-positive bacteria causing BSI in these patient populations. The high prevalence of VRE is similar to the overall prevalence of VRE among CLABSIs reported to NHSN. More data are needed on the epidemiology of healthcare-associated infections in these high-risk patients.

Table: NHSN BMT and HONC unit CLABSI incidence rates, by line type, 2006-2008 

	Temporary central lines1			Permanent central lines
Unit	# of units	DUR	Pooled mean2	# of units	DUR	Pooled mean2
BMT	18	0.28	3.52	21	0.60	3.88
Adult HONC	33	0.22	2.25	41	0.35	1.65
Pediatric HONC	5	0.22	4.57	7	0.63	2.33

¹Includes events in patients with temporary and permanent central lines in place.

²Per 1000 central line days.