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Importance of Bacterial Burden Among Methicillin-Resistant Staphylococcus aureus Carriers in a Long-Term Care Facility

Published online by Cambridge University Press:  02 January 2015

Nimalie D. Stone*
Affiliation:
Emory University School of Medicine, Emory University, Atlanta, Georgia
Donna R. Lewis
Affiliation:
Atlanta Veterans Administration Medical Center, Decatur, Georgia
H. K. Lowery
Affiliation:
Atlanta Veterans Administration Medical Center, Decatur, Georgia
Lyndsey A. Darrow
Affiliation:
Rollins School of Public Health, Emory University, Atlanta, Georgia
Catherine M. Kroll
Affiliation:
Rollins School of Public Health, Emory University, Atlanta, Georgia
Robert P. Gaynes
Affiliation:
Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia Atlanta Veterans Administration Medical Center, Decatur, Georgia
John A. Jernigan
Affiliation:
Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia
John E. McGowan Jr
Affiliation:
Rollins School of Public Health, Emory University, Atlanta, Georgia
Fred C. Tenover
Affiliation:
Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia
Chesley L. Richards Jr
Affiliation:
Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia
*
Division of Infectious Diseases, Wesley Woods Health Center, 1841 Clifton Rd., NE Room 527, Atlanta, GA 30329 (nstone@emory.edu)

Abstract

Objective.

To evaluate the prevalence and transmission of methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization, as well as risk factors associated with MRSA carriage, among residents of a long-term care facility (LTCF).

Design.

Prospective, longitudinal cohort study.

Setting.

A 100-bed Veterans Administration LTCF

Participants.

All current and newly admitted residents of the LTCF during an 8-week study period.

Methods.

Nasal swab samples were obtained weekly and cultured on MRSA-selective media, and the cultures were graded for growth on a semiquantitative scale from 0 (no growth) to 6 (heavy growth). Epidemiologic data for the periods before and during the study were collected to assess risk factors for MRSA carriage.

Results.

Of 83 LTCF residents, 49 (59%) had 1 or more nasal swab cultures that were positive for MRSA; 34 (41%) were consistently culture-negative (designated “noncarriers”). Of the 49 culture-positive residents, 30 (36% of the total of 83 residents) had all cultures positive for MRSA (designated “persistent carriers”), and 19 (23% of the 83 residents) had at least 1 culture, but not all cultures, positive for MRSA (designated “intermittent carriers”). Multivariate analysis showed that participants with at least 1 nasal swab culture positive for MRSA were likely to have had previous hospitalization (odds ratio, 3.9) or wounds (odds ratio, 8.2). Persistent carriers and intermittent carriers did not differ in epidemiologic characteristics but did differ in mean MRSA growth score (3.7 vs 0.7; P < .001).

Conclusions.

Epidemiologic characteristics differed between noncarriers and subjects with at least 1 nasal swab culture positive for MRSA. However, in this LTCF population, only the degree of bacterial colonization (as reflected by mean MRSA growth score) distinguished persistent carriers from intermittent carriers. Understanding the burden of colonization may be important when determining future surveillance and control strategies.

Type
Original Articles
Copyright
Copyright © The Society for Healthcare Epidemiology of America 2008

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