Importance of control group selection for evaluating antimicrobial use as a risk factor for methicillin-resistant Staphylococcus aureus bacteremia

Erika J Ernst; George Raley; Loreen A Herwaldt; Daniel J Diekema

doi:10.1086/502593

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Importance of control group selection for evaluating antimicrobial use as a risk factor for methicillin-resistant Staphylococcus aureus bacteremia

Journal article

Peer reviewed

Importance of control group selection for evaluating antimicrobial use as a risk factor for methicillin-resistant Staphylococcus aureus bacteremia

Erika J Ernst, George Raley, Loreen A Herwaldt and Daniel J Diekema

Infection control and hospital epidemiology, Vol.26(7), pp.634-637

07/2005

DOI: 10.1086/502593

PMID: 16092744

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Abstract

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. 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. 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. 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.

Methicillin Resistance - drug effects

Staphylococcal Infections - drug therapy

Cross Infection - prevention & control

Humans

Middle Aged

Risk Factors

Fluoroquinolones - therapeutic use

Male

Control Groups

Oxacillin - therapeutic use

Case-Control Studies

Patient Selection

Staphylococcal Infections - epidemiology

Epidemiologic Methods

Female

Iowa - epidemiology

Staphylococcal Infections - prevention & control

Anti-Bacterial Agents - adverse effects

Staphylococcus aureus - drug effects

Drug Utilization - statistics & numerical data

Length of Stay - statistics & numerical data

Details

Title: Subtitle: Importance of control group selection for evaluating antimicrobial use as a risk factor for methicillin-resistant Staphylococcus aureus bacteremia
Creators: Erika J Ernst - University of Iowa College of Pharmacy, Iowa City, Iowa 52242, USA. erika-ernst@uiowa.edu
George Raley
Loreen A Herwaldt
Daniel J Diekema
Resource Type: Journal article
Publication Details: Infection control and hospital epidemiology, Vol.26(7), pp.634-637
Publisher: United States
DOI: 10.1086/502593
PMID: 16092744
ISSN: 0899-823X
eISSN: 1559-6834
Language: English
Date published: 07/2005
Academic Unit: Infectious Diseases; Epidemiology; Pathology; Pharmacy Practice and Science; Internal Medicine
Record Identifier: 9983986365602771

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