477. Using a Point Prevalence Survey (PPS) to Estimate Incidence of Methicillin-Resistant Staphylococcus aureus (MRSA) Colonization Among Intensive Care Unit (ICU) Patients (pts) Across a Region
Session: Poster Session: Hospital-acquired and Transplant Infections
Friday, October 30, 2009: 12:00 AM
Room: Poster Hall A
Background: Illinois law mandates that ICU pts be screened for MRSA colonization on admission. We performed a PPS to detect MRSA colonization among Chicago ICU pts and assessed agreement with admission screening results on a subset of patients tested by both methods on ICU day 1. Excellent agreement would allow a PPS to estimate in-hospital MRSA colonization incidence for the entire PPS cohort.
Methods: Hospitals in Chicago with ≥10 ICU beds were recruited for a 1-day PPS in 7/08 - 1/09. All pts in ICUs were cultured for MRSA (nose/groin for adults and pediatrics; nose/umbilicus for neonates) using 1 swab for each site. All swabs were tested for MRSA using broth enrichment, chromogenic agar, and cefoxitin disk testing. Hospitals reported admission MRSA screening results for each pt. For pts screened by both hospital and PPS on ICU day 1, we calculated the kappa coefficient (Κ). MRSA colonization incidence was estimated per pt and per 1000 ICU-days.
Results: Among 26 hospitals, 825 of 839 eligible pts (493 adult, 83 pediatric, 249 neonatal) participated in the PPS. 95% (783 / 825) of study pts had an admission MRSA screen result. 95 pts had both admission and PPS screening performed on their first day of ICU stay: 9 were concordant +/+, 83 were concordant -/-, 1 was admission + / PPS -, and 2 were admission - / PPS +, Κ = 0.84 (95% confidence interval [CI] 0.66 - 1.00, P < 0.01). MRSA colonization incidence is shown (Table); the incidence density rate ratio for adult versus neonatal and pediatric units combined was 8.4 (95% CI 4.1 - 18.6, P < 0.01).
MRSA colonization incidencea, by patient type
Patient typeICU days at PPS, median (range)Incident MRSA+ pts at PPS, nTotal pts, NTotal adjusted ICU-daysbIncidence per pt (A/B)Incidence density per 1000 ICU-days (1000*A/C)
Neonatal18 (2-186)923373663.9%1.2
Pediatric8 (2-314)25811803.4%1.7
Adult5 (2-169)2935126918.3%10.8
a All data in table come from the cohort of pts who were MRSA negative at admission and participated in PPS on ICU day 2 or later.
b Adjusted ICU-days = [ICU-days of pts negative at PPS] + [(ICU-days of pts positive at PPS)/2]
Conclusion: Same-day paired PPS and ICU admission tests had excellent agreement, despite differences in personnel, number of sites swabbed, and laboratory methods. Therefore, point prevalence screening may allow for estimation of MRSA colonization incidence in regions where admission surveillance is already performed.
for the CDC Prevention Epicenters Program, Mary Hayden, MD, FSHEA2, Michael Lin, MD, MPH2, Karen Lolans, BS3, Rosie Lyles, MD, MHA4, William Trick, MD5, Stephen G. Weber, MD, MS6, Robert Weinstein, MD, FIDSA7 and  M. Y. Lin, None..
R. D. Lyles, None..
K. Lolans, None..
S. G. Weber, None. 
M. K. Hayden,
Sage Products Role(s): Grant Investigator, Received: Grant Recipient.
3M Company Role(s): Grant Investigator, Received: Grant Recipient.
R. A. Weinstein,
Sage Products Inc Role(s): Grant Investigator, Grant Investigator, Received: Research Grant, Speaker Honorarium.
Centers for Disease Control and Prevention Role(s): Board Member, Grant Investigator, Scientific Advisor (Review Panel or Advisory Committee), Board Member, Grant Investigator, Scientific Advisor (Review Panel or Advisory Committee), Received: Research Grant, Consulting Fee.
IDSA Role(s): Board Member, Board Member, Received: Other Financial Benefit.
W. E. Trick, None., (1)Rush University Medical Center, Chicago, IL, (2)Rush Univ. Med. Ctr., Chicago, IL, (3)Stroger Hospital (CCH), Chicago, IL, (4)Stroger Hosp. of Cook County, Chicago, IL, (5)The University of Chicago Medical Center, Chicago, IL, (6)Cook County Hospital, Rush Medical College, Chicago, IL


for the CDC Prevention Epicenters Program, None

M. Hayden, None

M. Lin, None

K. Lolans, None

R. Lyles, None

W. Trick, None

S. G. Weber, None

R. Weinstein, None