Methicillin-Resistant Staphylococcus aureus Central Line-Associated Bloodstream Infections in US Intensive Care Units, 1997-2007

Context Concerns about rates of methicillin- resistant Staphylococcus aureus ( MRSA) health care - associated infections have prompted calls for mandatory screening or reporting in efforts to reduce MRSA infections. Objective To examine trends in the incidence of MRSA central line - associated blood-stream infections ( BSIs) in US intensive care units ( ICUs). Design, Setting, and Participants Data reported by hospitals to the Centers for Disease Control and Prevention ( CDC) from 1997- 2007 were used to calculate pooled mean annual central line - associated BSI incidence rates for 7 types of adult and non-neonatal pediatric ICUs. Percent MRSA was defined as the proportion of S aureus central line - associated BSIs that were MRSA. We used regression modeling to estimate percent changes in central line - associated BSI metrics over the analysis period. Main Outcome Measures Incidence rate of central line - associated BSIs per 1000 central line days; percent MRSA among S aureus central line - associated BSIs. Results Overall, 33 587 central line - associated BSIs were reported from 1684 ICUs representing 16 225 498 patient- days of surveillance; 2498 reported central line - associated BSIs ( 7.4%) were MRSA and 1590 ( 4.7%) were methicillin- susceptible S aureus ( MSSA). Of evaluated ICU types, surgical, nonteaching- affiliated medical- surgical, cardiothoracic, and coronary units experienced increases in MRSA central line - associated BSI incidence in the 1997- 2001 period; however, medical, teaching- affiliated medical-surgical, and pediatric units experienced no significant changes. From 2001 through 2007, MRSA central line - associated BSI incidence declined significantly in all ICU types except in pediatric units, for which incidence rates remained static. Declines in MRSA central line associated BSI incidence ranged from - 51.5% ( 95% CI, - 33.7% to - 64.6%; P <. 001) in nonteaching- affiliated medical- surgical ICUs ( 0.31 vs 0.15 per 1000 central line days) to - 69.2% ( 95% CI, - 57.9% to - 77.7%; P <. 001) in surgical ICUs ( 0.58 vs 0.18 per 1000 central line days). In all ICU types, MSSA central line - associated BSI incidence declined from 1997 through 2007, with changes in incidence ranging from - 60.1% ( 95% CI, - 41.2% to - 73.1%; P <. 001) in surgical ICUs ( 0.24 vs 0.10 per 1000 central line days) to - 77.7% ( 95% CI, - 68.2% to - 84.4%; P <. 001) in medical ICUs ( 0.40 vs 0.09 per 1000 central line days). Although the overall proportion of S aureus central line associated BSIs due to MRSA increased 25.8% ( P=. 02) in the 1997- 2007 period, overall MRSA central line - associated BSI incidence decreased 49.6% ( P <. 001) over this period. Conclusions The incidence of MRSA central line - associated BSI has been decreasing in recent years in most ICU types reporting to the CDC. These trends are not apparent when only percent MRSA is monitored.