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404 A comparison of MRSA transmission rates in VA and Community long-term care facilities

Sunday, April 3, 2011
Trinity Ballroom (Hilton Anatole)
Christopher J. Crnich, MD, MS , William S. Middleton VA Hospital, Madison, WI
Patricia Filas-Mortensen, RN , School of Medicine and Public Health, University of Wisconsin, Madison, WI
Peggy Klokow , School of Medicine and Public Health, University of Wisconsin, Madison, WI
Megan Duster , School of Medicine and Public Health, University of Wisconsin, Madison, WI
Simone Warrack , School of Medicine and Public Health, University of Wisconsin, Madison, WI
David R. Zimmerman, PhD , School of Engineering, University of Wisconsin, Madison, WI
Background:  The Veterans Administration (VA) began to expand its successful hospital-based MRSA prevention bundle in its Community Living Centers (CLCs) in the middle of 2009. An ongoing longitudinal study of antibiotic resistance in community nursing homes (NHs) provided us with an opportunity to determine if rates of MRSA transmission between the two types of facilities were different.

Objective: Compare rates of MRSA transmission in VA CLCs and community NHs.

Methods:  Residents in 6 community NHs that had not implemented a MRSA control program underwent nasal cultures on a quarterly basis to detect incident MRSA colonization for a period of up to a year. Four consecutive quarters of data on MRSA transmissions on the long-term stay units of five VA CLCs in the same region were obtained from the Inpatient Evaluation Center (IPEC) database for comparison. Quarterly incidence density rates (IDRs) of MRSA transmissions (per 1,000 resident-days) were calculated for each facility. Quarterly and overall IDRs stratified by type of facility (VA versus community) were compared using Poisson regression.

Results:  There were 84 MRSA transmissions documented during 119,292 resident-days in VA CLCs (IDR = 0.70 per 1,000 resident-days [0.57 – 0.87]) and 57 MRSA transmissions were documented during 86,408 resident-days in community NHs (IDR = 0.66 per 1,000 resident-days [0.51 – 0.86]). Comparison of the IDRs did not identify any differences between VA and community facilities (IRR = 0.94, 95% CI = 0.67 – 1.31, P-value = 0.70). MRSA transmission IDRs were not found to be significantly different in any quarter where rates were compared (Table).

 

 

Facility Type

IRR

 

P-value

 

VA CLCs

Community NHs

Q1

0.97

0.66

0.67 (0.37 – 1.21)

0.18

Q2

0.50

0.62

1.24 (0.61 – 2.54)

0.55

Q3

0.69

0.57

0.82 (0.39 – 1.71)

0.60

Q4

0.64

0.84

1.31 (0.65 – 2.65)

0.46

Conclusions:  MRSA transmission rates on long-term stay units of VA CLCs are not appreciably different from those seen in community NHs in the same geographic region. These data raise questions about whether the MRSA prevention bundle is having an appreciable impact on MRSA transmission in VA CLCs and should prompt further investigation into the mechanisms of MRSA spread in this setting to determine if alternative methods for control should be explored.