Skip to main content Accessibility help

Protective Effect of Methicillin-Susceptible Staphylococcus aureus Carriage against Methicillin-Resistant S. aureus Acquisition in Nursing Homes: A Prospective Cross-Sectional Study

  • Rupak Datta (a1), Victor Quan (a1), Diane Kim (a1), Ellena M. Peterson (a2), Courtney Reynolds (a1), Hildy Meyers (a3), Michele Cheung (a3) and Susan S. Huang (a1) (a4)...



To evaluate whether an ecologic inverse association exists between methicillin-susceptible Staphylococcus aureus (MSSA) prevalence and methicillin-resistant S. aureus (MRSA) prevalence in nursing homes.


We conducted a secondary analysis of a prospective cross-sectional study of S. aureus prevalence in 26 nursing homes across Orange County, California, from 2008–2011. Admission prevalence was assessed using bilateral nares swabs collected from all new residents within 3 days of admission until 100 swabs were obtained. Point prevalence was assessed from a representative sample of 100 residents. Swab samples were plated on 5% sheep blood agar and Spectra MRSA chromogenic agar. If MRSA was detected, no further tests were performed. If MRSA was not detected, blood agar was evaluated for MSSA growth. We evaluated the association between MRSA and MSSA admission and point prevalence using correlation and linear regression testing.


We collected 3,806 total swabs. MRSA and MSSA admission prevalence were not correlated (r = −0.40, P = .09). However, MRSA and MSSA point prevalence were negatively correlated regardless of whether MSSA prevalence was measured among all residents sampled (r = −0.67, P = .0002) or among those who did not harbor MRSA (r = −0.41, P = .04). This effect persisted in regression models adjusted for the percentage of residents with diabetes (β = −0.73, P = .04), skin lesions (β = −1.17, P = .002), or invasive devices (β = −1.4, P = .0006).


The inverse association between MRSA and MSSA point prevalence and minimal association on admission prevalence suggest MSSA carriage may protect against MRSA acquisition in nursing homes. The minimal association on admission prevalence further suggests competition may occur during nursing home stays.

Infect Control Hosp Epidemiol 2014;35(10):1257–1262


Corresponding author

Health Policy Research Institute, University of California, Irvine School of Medicine, 100 Theory, Suite 110, Irvine, CA 92627 (


Hide All
1. Bowler, WA, Bresnahan, J, Bradfish, A, Fernandez, C. An integrated approach to methicillin-resistant Staphylococcus aureus control in a rural, regional-referral healthcare setting. Infect Control Hosp Epidemiol 2010;31:269275.
2. Fraise, AP, Mitchell, K, O’Brien, SJ, Oldfield, K, Wise, R. Methicillin-resistant Staphylococcus aureus (MRSA) in nursing homes in a major UK city: an anonymized point prevalence survey. Epidemiol Infect 1997;118:15.
3. Furuno, JP, Hebden, JN, Standiford, HC, et al. Prevalence of methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii in a long-term acute care facility. Am J Infect Control 2008;36:468471.
4. Mody, LC, Kauffman, A, Donabedian, S, Zervos, M, Bradley, SF. Epidemiology of Staphylococcus aureus colonization in nursing home residents. Clin Infect Dis 2008;46:13681373.
5. Murphy, CR, Quan, V, Kim, DS, et al. Nursing home characteristics associated with methicillin-resistant Staphylococcus aureus (MRSA) burden and transmission. BMC Infect Dis 2012;12:269.
6. Strausbaugh, LJ, Jacobson, C, Sewell, DL, Potter, S, Ward, TT. Methicillin-resistant Staphylococcus aureus in extended care facilities: experiences in a Veteran’s Affairs nursing home and a review of the literature. Infect Control Hosp Epidemiol 1991;13:711718.
7. Chamchod, F, Ruan, S. Modeling the spread of methicillin-resistant Staphylococcus aureus in nursing homes for elderly. PLoS ONE 2012;7:e29757.
8. Hughes, C, Smith, M, Tunney, M, Bradley, MC. Infection control strategies for preventing the transmission of meticillin-resistant Staphylococcus aureus (MRSA) in nursing homes for older people. Cochrane Database Syst Rev 2011;7:CD006354
9. Spindel, SJ, Strausbaugh, LFJ, Jacobson, C. Infections caused by Staphylococcus aureus in a Veterans’ Affairs nursing home care unit: a 5-year experience. Infect Control Hosp Epidemiol 1995;16:217223.
10. Storch, GA, Radcliff, JL, Meyer, PL, Hinrichs, JH. Methicillin-resistant Staphylococcos aureus in a nursing home. Infect Control Hosp Epidemiol 1987;8:2429.
11. Thomas, JC, Bridge, J, Waterman, S, Vogt, J, Kilman, L, Hancock, G. Transmission and control of methicillin-resistant Staphylococcus aureus in a skilled nursing facility. Infect Control Hosp Epidemiol 1989;10:106110.
12. Furuno, JP, Shurland, SM, Zhan, M, et al. Comparison of the methicillin-resistant Staphylococcus aureus acquisition among rehabilitation and nursing home residents. Infect Control Hosp Epidemiol 2011;32:244249.
13. Smith, PW, Bennett, G, Bradley, S, et al. SHEA/APIC guideline: infection prevention and control in the long-term care facility. Infect Control Hosp Epidemiol 2008;29:785814.
14. Strausbaugh, LJ, Sukumar, SR, Joseph, CL. Infectious disease outbreaks in nursing homes: an unappreciated hazard for frail elderly persons. Clin Infect Dis 2003;36:870876.
15. Trick, WE, Weinstein, RA, DeMarais, PL, et al. Colonization of skilled-care facility residents with antimicrobial-resistant pathogens. J Am Geriatr Soc 2001;49:270276.
16. Wang, L, Lansing, B, Symons, K, et al. Infection rate and colonization with antibiotic-resistant organisms in skilled nursing facility residents with indwelling devices. Eur J Clin Microbiol Infect Dis 2012;31:17971804.
17. Murphy, CR, Eells, SJ, Quan, V, et al. Methicillin-resistant Staphylococcus aureus burden in nursing homes associated with environmental contamination of common areas. J Am Geriatr Soc 2012;60:10121018.
18. Datta, R, Huang, SS. Risk of infection and death due to methicillin-resistant Staphylococcus aureus in long-term carriers. Clin Infect Dis 2008;47:176181.
19. Huang, SS, Hinrichsen, VL, Datta, R, et al. Methicillin-resistant Staphylococcus aureus infection and hospitalization in high-risk patients in the year following detection. PLoS ONE 2012;6:e24340.
20. Dall’Antonia, M, Coen, PG, Wilks, M, Whiley, A, Millar, M. Competition between methicillin-sensitive and -resistant Staphylococcus aureus in the anterior nares. J Hosp Infect 2005;61:6267.
21. Huang, SS, Datta, R, Rifas-Shiman, S, et al. Colonization with antibiotic-susceptible strains protects against methicillin-resistant Staphylococcus aureus but not vancomycin-resistant enterococci acquisition: a nested case-control study. Critical Care 2011;15:R210.
22. Edgeworth, JD. Has decolonization played a central role in the decline in UK methicillin resistant Staphylococcus aureus transmission? a focus on evidence from intensive care. J Antimicrob Chemother 2011;66:ii4147.
23. Engleman, R, Shahian, D, Shemin, R, et al. The Society of Thoracic Surgeons practice guidelines series: antibiotic prophylaxis in cardiac surgery, part II: antibiotic choice. Ann Thorac Surg 2007;83:15691576.
24. Fraser, TG, Fatica, C, Scarpelli, M, et al. Decrease in Staphylococcus aureus colonization and hospital-acquired infection in a medical intensive care unit after institution of an active surveillance and decolonization program. Infect Control Hosp Epidemiol 2010;31:779783.
25. Climo, MW, Yokoe, DS, Warren, DK, et al. Effect of daily chlorhexidine bathing on hospital-acquired infection. N Engl J Med 2013;368:533542.
26. Robicsek, A, Beaumont, JL, Thomson, RB, Govindarajan, G, Peterson, LR. Topical therapy for methicillin-resistant Staphylococcus aureus colonization: impact on infection risk. Infect Control Hosp Epidemiol 2009;30:623632.
27. Huang, SS, Septimus, E, Kleinman, K, et al. Targeted versus universal decolonization to prevent ICU infection. N Engl J Med 2013;368:22552265.
28. Davis, KA, Stewart, JJ, Crouch, HK, Florez, CE, Hospenthal, DR. Methicillin-resistant Staphylococcus aureus (MRSA) nares colonization at hospital admission and its effect on subsequent MRSA infection. Clin Infect Dis 2004;39:776782.
29. Honda, H, Krauss, MJ, Coopersmith, CM, et al. Staphylococcus aureus nasal colonization and subsequent infection in intensive care unit patients: does methicillin resistance matter? Infect Control Hosp Epidemiol 2010;31:584591.
30. Safdar, N, Bradley, EA. The risk of infection after nasal colonization with Staphylococcus aureus . Am J Med 2008;121:310315.
31. Blot, SI, Vandewoude, KH, Hoste, EA, Colardyn, FA. Outcome and attributable mortality in critically ill patients with bacteremia involving methicillin-susceptible and methicillin-resistant Staphylococcus aureus . Arch Intern Med 2002;162:22292235.
32. Cosgrove, SE, Sakoulas, G, Perencevich, EN, Schwaber, MJ, Karchmer, AW, Carmeli, Y. Comparison of mortality associated with methicillin-resistant and methicillin-susceptible Staphylococcus aureus bacteremia: a meta-analysis. Clin Infect Dis 2003;36:5359.
33. Cosgrove, SE, Qi, Y, Kaye, KS, Harbarth, S, Karchmer, AW, Carmeli, Y. The impact of methicillin resistance in Staphylococcus aureus bacteremia on patient outcomes: mortality, length of stay, and hospital charges. Infect Control Hosp Epidemiol 2005;26:166174.
34. Engemann, JJ, Carmeli, Y, Cosgrove, SE, et al. Adverse clinical and economic outcomes attributable to methicillin resistance among patients with Staphylococcus aureus surgical site infection. Clin Infect Dis 2003;36:592598.
35. Research Data Assistance Center. Accessed February 17, 2014.
36. Office of Statewide Health Planning and Development. Accessed February 17, 2014.
37. Kiely, DK, Flacker, JM. The protective effect of social engagement on 1-year mortality in a long-stay nursing home population. J Clin Epidemiol 2003;56:472478.

Protective Effect of Methicillin-Susceptible Staphylococcus aureus Carriage against Methicillin-Resistant S. aureus Acquisition in Nursing Homes: A Prospective Cross-Sectional Study

  • Rupak Datta (a1), Victor Quan (a1), Diane Kim (a1), Ellena M. Peterson (a2), Courtney Reynolds (a1), Hildy Meyers (a3), Michele Cheung (a3) and Susan S. Huang (a1) (a4)...


Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed