Skip to main content Accessibility help

Comparative Epidemiology of Bacteremia due to Methicillin-Resistant Staphylococcus aureus between Older and Younger Adults A Propensity Score Analysis

  • Ravina Kullar (a1), Michael J. Rybak (a2) and Keith S. Kaye (a3)



We evaluated the clinical and molecular epidemiology of bloodstream infections (BSIs) due to methicillin-resistant Staphylococcus aureus (MRSA) in older versus younger patients treated with vancomycin, determining the independent effect of increased age on outcomes.


Observational retrospective cohort study.


Detroit Medical Center, level I trauma center.


Adult older (65 years and older) and younger (younger than 65 years) patients with documented BSIs due to MRSA treated with vancomycin (2005–2010).


Collected demographics, comorbidities, microbiology, treatment, outcomes. Multivariable model used to generate propensity score for each patient on the basis of the probability of being 65 years of age or older.


Three hundred twenty patients were eligible (69 patients 65 years and older; 251 patients younger than 65 years). Catheter-related infections and endocarditis were the most common sites of infection for older (20.3%) and younger (19.1%) adults, respectively. Median first total 24-hour vancomycin dose (1,000 vs 2,000 mg; P< .001) and initial trough (13.1 vs 15.0 mg/L; P = .043) was significantly lower in older versus younger patients. Vancomycin treatment failure rates were similar among older and younger patients (49.3% vs 53.4%; P = .545). In multivariable analysis of outcomes, after controlling for predictors of older age, there was no difference in clinical outcomes between older and younger adults.


After accounting for confounders associated with increased age, failure rate of patients with BSIs due to MRSA treated with vancomycin was similar between older and younger patients. Older adults were less likely to have optimal vancomycin dosing and initial trough levels than younger patients. Efforts should be made to optimize dosing of medications such as vancomycin in older adults.


Corresponding author

Oregon State University/Oregon Health and Science University, 3303 Southwest Bond Avenue, CH12C, Portland, OR 97239 (


Hide All
1.Fowler, VG JrMiro, JM, Hoen, B, et al.Staphylococcus aureus endocarditis: a consequence of medical progress. JAMA 2005;293:30123021.
2.Hill, EE, Herijgers, P, Herregods, MC, et al.Evolving trends in infective endocarditis. Clin Microbiol Infect 2006;12:512.
3.National Nosocomial Infections Surveillance (NNIS) System Report, data summary from January 1992 through June 2004, issued October 2004. Am J Infect Control 2004;32:470485.
4.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.
5.Cosgrove, SE, Sakoulas, G, Perencevich, EN, et al.Comparison of mortality associated with methicillin-resistant and methicillin-susceptible Staphylococcus aureus bacteremia: a meta-analysis. Clin Infect Dis 2003;36:5359.
6.Lodise, TP, McKinnon, PS. Clinical and economic impact of methicillin resistance in patients with Staphylococcus aureus bacteremia. Diagn Microbiol Infect Dis 2005;52:113122.
7.McClelland, RS, Fowler, VG JrSanders, LL, et al.Staphylococcus aureus bacteremia among elderly vs younger adult patients: comparison of clinical features and mortality. Arch Intern Med 1999;159:12441247.
8.Lee, CC, Chen, SY, Chang, IJ, et al.Comparison of clinical manifestations and outcome of community-acquired bloodstream infections among the oldest old, elderly, and adult patients. Medicine 2007;86:138144.
9.Bradley, SF. Staphylococcus aureus infections and antibiotic resistance in older adults. Clin Infect Dis 2002;34:211216.
10.Bader, MS. Staphylococcus aureus bacteremia in older adults: predictors of 7-day mortality and infection with a methicillin-resistant strain. Infect Control Hosp Epidemiol 2006;27:12191225.
11.Kaye, KS, Marchaim, D, Chen, TY, et al.Predictors of nosocomial bloodstream infections in older adults. J Am Geriatr Soc 2011;59:622627.
12.Forsblom, E, Ruotsalainen, E, Molkanen, T, et al.Predisposing factors, disease progression and outcome in 430 prospectively followed patients of healthcare- and community-associated Staphylococcus aureus bacteraemia. J Hosp Infect 2011;78:102107.
13.Nolan, CM, Beaty, HN. Staphylococcus aureus bacteremia: current clinical patterns. Am J Med 1976;60:495500.
14.Levine, DP. Vancomycin: understanding its past and preserving its future. South Med J 2008;101:284291.
15.Kullar, R, Davis, SL, Levine, DP, et al.Impact of vancomycin exposure on outcomes in patients with methicillin-resistant Staphylococcus aureus bacteremia: support for consensus guide-lines suggested targets. Clin Infect Dis 2011;52:975981.
16.Sakoulas, G, Moise-Broder, PA, Schentag, J, et al.Relationship of MIC and bactericidal activity to efficacy of vancomycin for treatment of methicillin-resistant Staphylococcus aureus bacteremia. J Clin Microbiol 2004;42:23982402.
17.Rybak, MJ. The pharmacokinetic and pharmacodynamic properties of vancomycin. Clin Infect Dis 2006;42(suppl 1):S35S39.
18.Jones, RN. Microbiological features of vancomycin in the 21st century: minimum inhibitory concentration creep, bactericidal/static activity, and applied breakpoints to predict clinical outcomes or detect resistant strains. Clin Infect Dis 2006;42(suppl 1):S13S24.
19.Kollef, MH. Limitations of vancomycin in the management of resistant staphylococcal infections. Clin Infect Dis 2007;45(suppl 3):S191S195.
20.Soriano, A, Marco, F, Martinez, JA, et al.Influence of vancomycin minimum inhibitory concentration on the treatment of methicillin-resistant Staphylococcus aureus bacteremia. Clin Infect Dis 2008;46:193200.
21.Khatib, R, Johnson, LB, Fakih, MG, et al.Persistence in Staphylococcus aureus bacteremia: incidence, characteristics of patients and outcome. Scand J Infect Dis 2006;38:714.
22.Lodise, TP, Lomaestro, B, Graves, J, et al.Larger vancomycin doses (at least four grams per day) are associated with an increased incidence of nephrotoxicity. Antimicrob Agents Chemother 2008;52:13301336.
23.Fowler, VG JrSakoulas, G, McIntyre, LM, et al.Persistent bacteremia due to methicillin-resistant Staphylococcus aureus infection is associated with agr dysfunction and low-level in vitro resistance to thrombin-induced platelet microbicidal protein. J Infect Dis 2004;190:11401149.
24.Hawkins, C, Huang, J, Jin, N, et al.Persistent Staphylococcus aureus bacteremia: an analysis of risk factors and outcomes. Arch Intern Med 2007;167:18611867.
25.Levine, DP, Fromm, BS, Reddy, BR. Slow response to vancomycin or vancomycin plus rifampin in methicillin-resistant Staphylococcus aureus endocarditis. Ann Intern Med 1991;115:674680.
26.Garner, JS, Jarvis, WR, Emori, TG, et al.CDC definitions for nosocomial infections, 1988. Am J Infect Control 1988;16:128140.
27.Clinical and Laboratory Standards Institute (CLSI). Methods for Dilution Antimicrobial Susceptibility Test for Bacteria That Grow Aerobically; Approved Standard. 8th ed. Wayne, PA: CLSI, 2009. CLSI document M7-A8.
28.Rybak, MJ, Leonard, SN, Rossi, KL, et al.Characterization of vancomycin-heteroresistant Staphylococcus aureus from the metropolitan area of Detroit, Michigan, over a 22-year period (1986 to 2007). J Clin Microbiol 2008;46:29502954.
29.Wootton, M, MacGowan, AP, Walsh, TR, et al.A multicenter study evaluating the current strategies for isolating Staphylococcus aureus strains with reduced susceptibility to glycopeptides. J Clin Microbiol 2007;45:329332.
30.Zhang, K, McClure, JA, Elsayed, S, et al.Novel multiplex PCR assay for characterization and concomitant subtyping of staphylococcal cassette chromosome mec types I to V in methicillin-resistant Staphylococcus aureus. J Clin Microbiol 2005;43:50265033.
31.Lina, G, Piemont, Y, Godail-Gamot, F, et al.Involvement of Panton-Valentine leukocidin-producing Staphylococcus aureus in primary skin infections and pneumonia. Clin Infect Dis 1999;29:11281132.
32.Freeborne, N, Lynn, J, Desbiens, NA. Insights about dying from the SUPPORT project: the Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments. J Am Geriatr Soc 2000;48:S199S205.
33.Levinsky, NG, Yu, W, Ash, A, et al.Influence of age on Medicare expenditures and medical care in the last year of life. JAMA 2001;286:13491355.
34.Hiramatsu, K, Cui, L, Kuroda, M, et al.The emergence and evolution of methicillin-resistant Staphylococcus aureus. Trends Microbiol 2001;9:486493.
35.Herold, BC, Immergluck, LC, Maranan, MC, et al.Community-acquired methicillin-resistant Staphylococcus aureus in children with no identified predisposing risk. JAMA 1998;279:593598.
36.Naimi, TS, LeDell, KH, Como-Sabetti, K, et al.Comparison of community- and health care-associated methicillin-resistant Staphylococcus aureus infection. JAMA 2003;290:29762984.


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