Improving methicillin-resistant Staphylococcus aureus surveillance and reporting in intensive care units.
BACKGROUND
Routine culturing of patients in intensive care units (ICUs) for methicillin-resistant Staphylococcus aureus (MRSA) identifies unrecognized carriers and facilitates timely isolation. However, the benefit of surveillance in detecting prevalent and incident carriers likely varies among ICUs. In addition, many assessments underestimate the incidence of acquisition by including prevalent carriers in the at-risk population.


METHODS
We performed a retrospective cohort study using accurate at-risk populations to evaluate the range of benefit of admission and weekly surveillance cultures in detecting otherwise unrecognized MRSA in 12 ICUs in 5 states.


RESULTS
We assessed 142 ICU-months. Among the 12 ICUs, the admission prevalence of imported MRSA was 5%-21%, with admission surveillance providing 30%-135% increases in rates of detection. The monthly hospital-associated incidence was 2%-6%, with weekly surveillance providing 7%-157% increases in detection. The common practice of reporting incidence using the total number of patients or total patient-days underestimated incidence by one-third. Surgical ICUs had lower MRSA importation but higher MRSA incidence. Overall, routine surveillance prevented the misclassification of 17% (unit range, 11%-29%) of "incident" carriers, compared with clinical cultures, and increased precaution days by 18% (unit range, 11%-91%).


CONCLUSIONS
Routine surveillance significantly increases the detection of MRSA, but this benefit is not uniform across ICUs, even with high compliance and the use of correct denominators.
Huang
Susan S
SS
Brigham and Women's Hospital, Channing Laboratory and Infection Control Department, Harvard Medical School, and Harvard Pilgrim Health Care, Boston, MA 02115, USA. sshuang@partners.org
Rifas-Shiman
Sheryl L
SL
Warren
David K
DK
Fraser
Victoria J
VJ
Climo
Michael W
MW
Wong
Edward S
ES
Cosgrove
Sara E
SE
Perl
Trish M
TM
Pottinger
Jean M
JM
Herwaldt
Loreen A
LA
Jernigan
John A
JA
Tokars
Jerome L
JL
Diekema
Daniel J
DJ
Hinrichsen
Virginia L
VL
Yokoe
Deborah S
DS
Platt
Richard
R
D000046:Academic Medical Centers; D002353:Carrier State / Q000175:diagnosis / Q000517:prevention & control*; D015331:Cohort Studies; D003955:Diagnostic Tests, Routine / Q000592:standards*; D018563:Disease Notification; D018562:Disease Transmission, Infectious / Q000517:prevention & control; D006801:Humans; D015994:Incidence; D007362:Intensive Care Units; D008712:Methicillin / Q000494:pharmacology*; D016106:Methicillin Resistance; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D018571:Sentinel Surveillance; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000517:prevention & control*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification*; D014481:United States / Q000453:epidemiology
D008712:Methicillin