Hostname: page-component-78c5997874-t5tsf Total loading time: 0 Render date: 2024-11-19T11:59:03.619Z Has data issue: false hasContentIssue false
  • English
  • Français

Importance of Control Group Selection for Evaluating Antimicrobial Use as a Risk Factor for Methicillin-Resistant Staphylococcus Aureus Bacteremia

Published online by Cambridge University Press:  21 June 2016

Erika J. Ernst ,
George Raley ,
Loreen A. Herwaldt  and
Daniel J. Diekema
Erika J. Ernst*
Affiliation:
University of Iowa College of Pharmacy, Iowa City, Iowa
George Raley
Affiliation:
University of Iowa College of Pharmacy, Iowa City, Iowa
Loreen A. Herwaldt
Affiliation:
Department of Internal Medicine, the University of Iowa College of Medicine; and the University of Iowa Hospitals and Clinics, Iowa City, Iowa Department of Epidemiology, the University of Iowa College of Public Health, Iowa City, Iowa
Daniel J. Diekema
Affiliation:
Department of Pathology, the University of Iowa College of Medicine; and the Veterans Affairs Medical Center, Iowa City, Iowa
*
University of Iowa, College of Pharmacy, S428 Pharmacy Building, Iowa City, IA 52242.erika-ernst@uiowa.edu
Get access Rights & Permissions [Opens in a new window]

Abstract

Objective:

We investigated the importance of control group selection during an evaluation of antimicrobial use as a risk factor for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia at our institution.

Methods:

We performed a case-control study. A case was defined as any patient admitted between January 1997 and May 2001 who developed nosocomial MRSA bacteremia. We used two control groups; control group I consisted of patients with nosocomial methicillin-susceptible S. aureus (MSSA) bacteremia and control group II included only patients without bacteremia. We matched control-patients to case-patients using age, gender, time at risk, and hospital ward. Data collected on all patients included demographics, comorbidities, antibiotic use, time at risk, length of stay, severity of illness, and outcome.

Results:

We evaluated 63 patients (21 in each group). The three groups were well matched regarding age, gender, underlying diseases, and severity of illness. Patients in the MRSA group were more likely to have received a fluoroquinolone and had a higher mean number of days of fluoroquinolone use than did patients in the MSSA group (P = .027 and P = .015, respectively). However, all measures of fluoroquinolone use were similar for case-patients and for control-patients who did not have nosocomial bloodstream infection.

Conclusions:

Control group selection is important in evaluating antimicrobial use as a risk factor for MRSA bacteremia. Using control-patients infected with MSSA, rather than uninfected control-patients, may overestimate the association between antimicrobial use and MRSA infection. (Infect Control Hosp Epidemiol 2005;26:634-637)

Type
Original Articles
Information
Infection Control & Hospital Epidemiology , Volume 26 , Issue 7 , July 2005 , pp. 634 - 637
Copyright
Copyright © The Society for Healthcare Epidemiology of America 2005

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1.Muto, CA, Jernigan, JA, Ostrowski, BE, et al.SHEA guideline for preventing nosocomial transmission of multidrug-resistant strains of Staphylococcus aureus and Enterococcus. Infect Control Hosp Epidemiol 2003;24:362–386.Google Scholar
2.Dziekan, G, Hahn, A, Thune, K, et al.Methicillin-resistant Staphylococcus aureus in a teaching hospital: investigation of nosocomial transmission using a matched case-control study. J Hosp Infect 2000;46:263–270.CrossRefGoogle Scholar
3.Graffunder, EM, Venezia, RA. Risk factors associated with nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infection including previous use of antimicrobials. J Antimicrob Chemother 2002; 49:999–1005.Google Scholar
4.Weber, SG, Gold, HS, Hooper, DC, Karchmer, AW, Carmeli, Y. Fluoroquinolones and the risk for methicillin-resistant Staphylococcus aureus in hospitalized patients. Emerg Infect Dis 2003;9:1415–1422.CrossRefGoogle ScholarPubMed
5.Harbarth, S, Harris, AD, Carmeli, Y, Samore, MH. Parallel analysis of individual and aggregated data on antibiotic exposure and resistance in gram-negative bacilli. Clin Infect Dis 2001;33:1462–1468.CrossRefGoogle ScholarPubMed
6.Harris, AD, Karchmer, TB, Carmeli, Y, Samore, MH. Methodological principles of case-control studies that analyzed risk factors for antibiotic resistance: a systematic review. Clin Infect Dis 2001;32:1055–1061.Google Scholar
7.Harris, AD, Samore, MH, Carmeli, Y. Control group selection is an important but neglected issue in studies of antibiotic resistance. Ann Intern Med 2000;133:159.Google Scholar
8.Harris, AD, Samore, MH, Lipsitch, M, et al.Control-group selection importance in studies of antimicrobial resistance: examples applied to Pseudomonas aeruginosa, Enterococcus, and Escherichia coli. Clin Infect Dis 2002;34:1558–1563.CrossRefGoogle ScholarPubMed
9.Patterson, DL. Looking for risk factors for the acquisition of antibiotic resistance: a 21st-century approach. Clin Infect Dis 2002;34:1564–1567.CrossRefGoogle Scholar
10.Charlson, ME, Pompei, P, Ales, KL, MacKenzie, CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 1987;40:373–383.CrossRefGoogle ScholarPubMed
11.Fridkin, SK, Steward, CD, Edwards, JR, et al. Surveillance of antimicrobial use and antimicrobial resistance in United States hospitals: Project ICARE phase 2. Project Intensive Care Antimicrobial Resistance Epidemiology (ICARE) hospitals. Clin Infect Dis 1999;29:245–252.Google Scholar
12.Pittet, D, Tarara, D, Wenzel, RP. Nosocomial bloodstream infection in critically ill patients: excess length of stay, extra costs, and attributable mortality. JAMA 1994;271:1598–1601.CrossRefGoogle ScholarPubMed
13.Crowcroft, NS, Ronveaux, O, Monnet, DL, Mertens, R. Methicillin-resistant S. aureus and antimicrobial use in Belgian hospitals. Infect Control Hosp Epidemiol 1999;20:31–36.CrossRefGoogle ScholarPubMed