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Influx of Multidrug-Resistant, Gram-Negative Bacteria in the Hospital Setting and the Role of Elderly Patients With Bacterial Bloodstream Infection

  • Aurora Pop-Vicas (a1), E. Tacconelli (a2), Stefan Gravenstein (a3), Bing Lu (a4) and Erika M. C. D'Agata (a5)...

Multidrug-resistant (MDR) gram-negative bacteria are reported increasingly frequently among isolates recovered from elderly patients. The clinical epidemiology of bloodstream infection (BSI) due to MDR gram-negative bacteria among elderly patients is unknown.


To characterize the clinical epidemiology of BSI due to MDR gram-negative bacteria among elderly patients at hospital admission in an effort to provide a greater understanding of these serious infections and ultimately to improve patient outcomes.


Case-control study.


Tertiary care hospital in Boston, Massachusetts.


Patients 65 years of age and older.


From 1999 to 2007, computerized medical records were reviewed for BSI due to MDR gram-negative bacteria within 48 hours of hospital admission. Risk factors for BSI due to these bacteria were identified.


MDR gram-negative bacteria were recovered from 61 (8%) of 724 elderly patients with BSI caused by gram-negative bacteria. Over the -year study period, the percentage of MDR gram-negative bacteria among bloodstream isolates increased from 2 (1%) of 199 to 34 (16%) of 216. Empiric therapy was ineffective for 38 (63%) of 60 patients with BSI caused by MDR gram-negative bacteria. The variables independently associated with BSI due to these bacteria were as follows: residency in a long-term care facility (odds ratio [OR], 4.9 [95% confidence interval {CI} 1.6–14.9]; P = .006), presence of an invasive device (OR, 6.0 [95% CI, 1.5–23.5]; P = .01), severe sepsis (OR, 7.9 [95% CI, 1.7–37.1]; P = .009), and delayed initiation of effective therapy (OR, 12.8 [95% CI, 3.9–41.1]; P<.001).


The 16-fold increase in BSI due to MDR gram-negative bacteria at hospital admission among elderly patients, especially among those who resided in long-term care facilities prior to admission, contributes further to the expanding body of evidence that these patients are the main reservoirs of MDR gram-negative bacteria. Given their contribution to the influx of antimicrobial-resistant bacteria in the hospital setting, infection control interventions that target this high-risk group need to be considered.

Corresponding author
Beth Israel Deaconess Medical Center, Division of Infectious Diseases, 330 Brookline Ave., East Campus Mailstop SL-435G, Boston, MA 02215 (
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1.Blot, S, Vandewoude, K, De Bacquer, D, et al.Nosocomial bacteremia caused by antibiotic-resistant gram-negative bacteria in critically ill patients: clinical outcome and length of hospitalization. Clin Infect Dis 2002;34:16001606.
2.Martin, GS, Mannino, DM, Moss, M. The effect of age on the development and outcome of adult sepsis. Crit Care Med 2006;34:1521.
3.Jones, RN. Resistance patterns among nosocomial pathogens: trend over the past years. Chest 2001;119(S2):397S404S.
4.Flournoy, DJ, Reinert, RL, Bell-Dixon, C, et al.Increasing antimicrobial resistance in gram-negative bacilli isolated from patients in intensive care units. Am J Infect Control 2000;28:244250.
5.D'Agata, EMC. Rapidly rising prevalence of nosocomial multidrug-resistant, gram-negative bacilli: a 9-year surveillance study. Infect Control Hosp Epidemiol 2004;25:842846.
6.Karlowsky, JA, Jones, ME, Thornsberry, C, Friedland, IR, Sahm, DF. Trends in antimicrobial susceptibilities among Enterobacteriaceae isolates from hospitalized patients in the United States from 1998 to 2001. Antimicrob Agents Chemother 2003;47:16721680.
7.National Noscomial Infections Surveillance System 2004. Data summary from January 1992 through June 2004, issued October 2004. Am J Infect Control 2004;32:470485.
8.O'Fallon, E, Pop-Vicas, A, D'Agata, EMC. The emerging threat of multi-drug resistant gram-negative organisms in a long-term care facilities. J Gerontol A Biol Sci Med Sci 2009 (in press).
9.Pop-Vicas, AE, D'Agata, EM. The rising influx of multidrug-resistant gram-negative bacilli into a tertiary care hospital. Clin Infect Dis 2005;40:17921798.
10.Garner, JS, Jarvis, WR, Emori, TG, Horan, TC, Hughes, J. CDC definitions for nosocomial infections, 1988. Am J Infect Control 1988;16:128140.
11.Yu, VL, Chiou, CC, Feldman, C, et al.An international prospective study of pneumococcal bacteremia: correlation with in vitro resistance, anti-biotics administered, and clinical outcome. Clin Infect Dis 2003;37:230237.
12.Paterson, DL, Ko, WC, Von Gottberg, S, et al.International prospective study of Klebsiella pneumoniae bacteremia: implications of extended-spectrum beta-lactamase production in nosocomial infections. Ann Intern Med 2004;140:2632.
13.Charlson, M, Pompei, P, Ales, K, MacKenzie, CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chron Dis 1987;40:373383.
14.Clinical and Laboratory Standards Institute (CLSI). Performance standards for antimicrobial susceptibility testing: supplement M100-S16. Wayne, PA: CLSI, 2006.
15.Pfaller, MA, Segreti, J. Overview of the epidemiological profile and laboratory detection of extended-spectrum β-lactamases. Clin Infect Dis 2006;42(suppl 4):S153S163.
16.Opal, SM, Girard, TD, Ely, WE. The immunopathogenesis of sepsis in elderly patients. Clin Infect Dis 2005;41:S504S512.
17.Harbarth, S, Garbino, J, Pugin, J, et al.Inappropriate initial antimicrobial therapy and its effect on survival in a clinical trial of immunomodulating therapy for severe sepsis. Am J Med 2003;115:529535.
18.Garnacho-Montero, J, Garcia-Garmendia, JL, Barrero-Almodovar, A, et al.Impact of adequate empirical antibiotic therapy on the outcome of patients admitted to the intensive care unit with sepsis. Crit Care Med 2003;31:27422751.
19.Peralta, G, Sanchez, MB, Garrido, JC, et al.Impact of antibiotic resistance and of adequate empirical antibiotic treatment in the prognosis of patients with Escherichia coli bacteraemia. J Antimicrob Chemother 2007;60:855863.
20.Kumar, A, Roberts, D, Wood, KE, et al.Duration of hypotension prior to initiation of effective antimicrobial therapy is the critical determinant of survival in human septic shock. Crit Care Med 2006;34:15891596.
21.Wiener, J, Quinn, JP, Bradford, PA, et al.Multiple antibiotic-resistant Klebsiella and Escherichia coli in nursing homes. JAMA 1999;281:517523.
22.Trick, W, Weinstein, RA, DeMarais, PL, et al.Colonization of skilled-care facility residents with antimicrobial-resistant pathogens. J Am Geriatr Soc 2001;49:270276.
23.Bonomo, R. Multiple antibiotic-resistant bacteria in long-term-care facilities: an emerging problem in the practice of infectious diseases. Clin Infect Dis 2000;31:14141422.
24.Nicolle, LE. Preventing infections in non-hospital settings: long-term care. Emerg Infect Dis 2001;7:205207.
25.Loeb, M, Simor, AE, Landry, L, et al.Antibiotic use in Ontario facilities that provide chronic care. J Gen Intern Med 2001;16:376383.
26.Warren, JW, Palumbo, FB, Fitterman, L, Speedie, SM. Incidence and characteristics of antibiotic use in aged nursing home patients. J Am Geriatr Soc 1991;39:963972.
27.Zimmer, JG, Bentley, DW, Valenti, WM, et al.Systemic antibiotic use in nursing homes: a quality assessment. J Am Geriatr Soc 1986;34:703710.
28.Pickering, TD, Gurwitz, JH, Zaleznik, D, et al.The appropriateness of oral fluoroquinolone-prescribing in the long-term care setting. J Am Geriatr Soc 1994;42:2832.
29.Jones, SR, Parker, DF, Liebow, ES, et al.Appropriateness of antibiotic therapy in long-term care facilities. Am J Med 1987;83:499502.
30.D'Agata, EMC, Mitchell, SL. Patterns of antimicrobial use among nursing home residents with advanced dementia. Arch Intern Med 2008;168:357362.
31.Pop-Vicas, A, Strom, T, D'Agata, EMC. Multidrug-resistant gram-negative bacilli among patients who require chronic hemodialysis. Clin J Am Soc Nephrol 2008;3:752758.
32.Nicolle, LE, Bentley, D, Garibaldi, R, et al.Antimicrobial use in long-term-care facilities. Infect Control Hosp Epidemiol 1996;17:119128.
33.D'Agata, EMC. Methodological issues of case-control studies: a review of established and newly recognized limitations. Infect Control Hosp Epidemiol 2005;26:338341.
34.Falagas, M, Koletsi, P, Bliziotis, I. The diversity of definitions of multidrug-resistant (MDR) and pandrug-resistant (PDR) Acinetobacter baumannii and Pseudomonas aeruginosa. J Med Microbiol 2006;55:16191629
35.Harris, AD, Samore, MH, Lipsitch, M, et al.Control-group selection importance in studies of antimicrobial resistance: examples applied to Pseudomonas aeruginosa, Enterococci, and Escherichia coli. Clin Infect Dis 2002;34:15581563.
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Infection Control & Hospital Epidemiology
  • ISSN: 0899-823X
  • EISSN: 1559-6834
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