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Imipenem Resistance in Pseudomonas aeruginosa Emergence, Epidemiology, and Impact on Clinical and Economic Outcomes

  • Ebbing Lautenbach (a1) (a2) (a3) (a4), Marie Synnestvedt (a4), Mark G. Weiner (a5) (a4), Warren B. Bilker (a2) (a3) (a4), Lien Vo (a6), Jeff Schein (a6) and Myoung Kim (a6)...

Pseudomonas aeruginosa is one of the most common gram-negative hospital-acquired pathogens. Resistance of this organism to imipenem complicates treatment.


To elucidate the risk factors for imipenem-resistant P. aeruginosa (IRPA) infection or colonization and to identify the effect of resistance on clinical and economic outcomes.


Longitudinal trends in prevalence of IRPA from 2 centers were characterized during the period from 1989 through 2006. For P. aeruginosa isolates obtained during the period from 2001 through 2006, a case-control study was conducted to investigate the association between prior carbapenem use and IRPA infection or colonization, and a cohort study was performed to identify the effect of IRPA infection or colonization on mortality, length of stay after culture, and hospital cost after culture.


From 1989 through 2006, the proportion of P. aeruginosa isolates demonstrating resistance to imipenem increased from 13% to 20% (P< .001, trend). During the period from 2001 through 2006, there were 2,542 unique patients with P. aeruginosa isolates, and 253 (10.0%) had IRPA isolates. Prior carbapenem use was independently associated with IRPA infection or colonization (adjusted odds ratio [OR], 7.92 [95% confidence interval {CI}, 4.78-13.11]). Patients with an IRPA isolate recovered had higher in-hospital mortality than did patients with an imipenem-susceptible P. aeruginosa isolate (17.4% vs 13.4%; P = .01). IRPA infection or colonization was an independent risk factor for mortality among patients with isolates recovered from blood (adjusted OR, 5.43 [95% CI, 1.72-17.10]; P = .004) but not among patients with isolates recovered from other anatomic sites (adjusted OR, 0.78 [95% CI, 0.51-1.21]; P = .27). Isolation of IRPA was associated with longer hospital stay after culture (P<.001) and greater hospital cost after culture (P<.001) than was isolation of an imipenem-susceptible strain. In multivariable analysis, IRPA infection or colonization remained an independent risk factor for both longer hospital stay after culture (coefficient, 0.20 [95% CI, 0.04-0.36]; P = .02) and greater hospital cost after culture (coefficient, 0.30 [95% CI, 0.06-0.54]; P = .02).


The prevalence of IRPA infection or colonization has increased significantly, with important implications for both clinical and economic outcomes. Interventions to curb this continued increase and strategies to optimize therapy are urgently needed.

Corresponding author
Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, 825 Blockley Hall, 423 Guardian Drive, Philadelphia, PA 191046021 (
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1. AC Fluit , ME Jones , FJ Schmitz , J Acar , R Gupta , J Verhoef . Antimicrobial susceptibility and frequency of occurrence of clinical blood isolates in Europe from the SENTRY antimicrobial surveillance program, 1997 and 1998. Clin Infect Dis 2000;30:454460.

3. M Hilf , VL Yu , JA Sharp , JJ Zuravleff , JA Korvick , RR Muder . Antibiotic therapy for Pseudomonas aeruginosa bacteremia: outcome correlation in a prospective study of 200 patients. Am J Med 1989;87:540546.

4. ST Micek , AE Lloyd , DJ Ritchie , RM Reichley , VJ Fraser , MH Kollef . Pseudomonas aeruginosa bloodstream infection: importance of appropriate initial antimicrobial treatment. Antimicrob Agents Chemother 2005;49:13061311.

5. F Vidal , J Mensa , M Alrnela , et al. Epidemiology and outcome of Pseudomonas aeruginosa bacteremia, with special emphasis of the influence of antibiotic treatment. Arch Intern Med 1996;156:21212126.

6. DL Paterson . The epidemiological profile of infections with multidrug-resistant Pseudomonas aeruginosa and Acinetobacter species. Clin Infect Dis 2006;43(Suppl 2):4348.

7. JE McGowan . Resistance in nonfermenting gram-negative bacteria: multidrug resistance to the maximum. Am J Med 2006;119(Suppl 1):S29S36.

8. AD Harris , TB Karchmer , Y Carmeli , MH Samore . Methodological principles of case-control studies that analyzed risk factors for antibiotic resistance: a systematic review. Clin Infect Dis 2001;32:10551061.

10. E Lautenbach , MG Weiner , I Nachamkin , WB Bilker , A Sheridan , NO Fishman . Imipenem resistance among Pseudomonas aeruginosa isolates: risk factors for infection and impact of resistance on clinical and economic outcomes. Infect Control Hosp Epidemiol 2006;27:893900.

12. C Defez , P Fabbro-Peray , N Bouziges , et al. Risk factors for multidrug-resistant Pseudomonas aeruginosa nosocomial infection. J Hosp Infect 2004;57:209216.

13. ME Falagas , PK Koletsi , IA Bliziotis . The diversity of definitions of mul-tidrug-resistant (MDR) and pandrug-resistant (PDR) Atinetobacter bau-mannii and Pseudomonas aeruginosa. J Med Microbiol 2006;55:16191629.

14. H MacAdam , TE Zaoutis , LB Gasink , WB Bilker , E Lautenbach . Investigating the association between antibiotic use and antibiotic resistance: impact of different methods of categorizing prior antibiotic use. Int J Antimicrob Agents 2006;28:325332.

15. LB Gasink , TE Zaoutis , WB Bilker , E Lautenbach . The categorization of prior antibiotic use: impact of the identification of risk factors for drug resistance in case control studies. Am J Infect Control 2007;35:638642.

16. P Armitage . Test for linear trend in proportions and frequencies. Biometrics 1955;11:375386.

20. GW Sun , TL Shook , GL Kay . Inappropriate use of bivariable analysis to screen risk factors for use in multivariable analysis. J Clin Epidemiol 1996;49:907916.

22. JS Garner , WR Jarvis , TG Emori , TC Horau , JM Hughes . CDC definitions for nosocomial infections, 1988. Am J Infect Control 1988;16:128140.

23. Z Ozkurt , M Ertek , S Eroi , U Altoparlak , MN Akcay . The risk factors for acquisition of imipenem-resistant Pseudomonas aeruginosa in the burn unit. Burns 2005;31:870873.

24. CM Fortaleza , MP Freira , D Filho , M de Carvalho Ramos . Risk factors for recovery of imipenem- or ceftazidime-resistant Pseudomonas aeruginosa among patients admitted to a teaching hospital in Brazil. Infect Control Hosp Epidemiol 2006;27:901906.

25. B Cao , H Wang , H Sun , Y Zhu , M Chen . Risk factors and clinical outcomes of nosocomial multi-drug resistant Pseudomonas aeruginosa infections. J Hosp Infect 2004;57:112118.

26. AD Harris , D Smith , JA Johnson , DD Bradham , MC Roghmann . Risk factors for imipenem-resistant Pseudomonas aeruginosa among hospitalized patients. Clin Infect Dis 2002;34:340345.

27. N Troillet , MH Samore , Y Carmeli . Imipenem-resistant Pseudomonas aeruginosa: risk factors and antibiotic susceptibility patterns. Clin Infect Dis 1997;25:10941098.

29. C Peña , A Guzmán , C Suarez , et al. Effects of carbapenem exposure of the risk for digestive tract carriage of intensive care unit-endemic car-bapenem-resistant Pseudomonas aeruginosa strains in critically ill patients. Antimicrob Agents Chemother 2007;51:19671971.

30. LJ Strausbaugh , KB Crossley , BA Nurse , LD Thrupp . Antimicrobial resistance in long-term care facilities. Infect Control Hosp Epidemiol 1996;17:129140.

31. E Lautenbach , NO Fishman , WB Bilker , et al. Risk factors for fluoroquinolone resistance in nosocomial Escherichia coli and Klebsiella pneumoniae infections. Arch Intern Med 2002;162:24692477.

32. E Lautenbach , BL Strom , WB Bilker , JB Patel , PH Edelstem , NO Fishman . Epidemiological investigation of fluoroquinolone resistance in infections due to extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae. Clin Infect Dis 2001;33:12881294.

34. Y Carmeli , N Troillet , AW Karchmer , M Samore . Health and economic outcomes of antibiotic resistance in Pseudomonas aeruginosa. Arch Intern Med 1999;159:11271132.

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Infection Control & Hospital Epidemiology
  • ISSN: 0899-823X
  • EISSN: 1559-6834
  • URL: /core/journals/infection-control-and-hospital-epidemiology
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