Bacteriology
Four-year prospective evaluation of community-acquired bacteremia: epidemiology, microbiology, and patient outcome

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Abstract

The objectives of this study were to (1) describe the epidemiology and microbiology of community-acquired bacteremia; (2) determine the crude mortality associated with such infections; and (3) identify independent predictors of mortality. All patients with clinically significant community-acquired bacteremia admitted to a university-affiliated Veterans Affairs medical center from January 1994 through December 1997 were evaluated. During the study period, 387 bacteremic episodes occurred in 334 patients. Staphylococcus aureus, Escherichia coli, and coagulase-negative staphylococci were the most commonly isolated organisms; the most frequent sources were the urinary tract and intravascular catheters. Approximately 14% of patients died. Patient characteristics independently associated with increased mortality included shock (OR 3.7, p = 0.02) and renal failure (OR 4.0, p = 0.003). The risk of death was also higher in those whose source was pneumonia (OR 6.3, p = 0.03) or an intra-abdominal site (OR 10.7, p = 0.02), or if multiple sources were identified (OR 13.4, p = 0.003). Community-acquired bacteremia is often device-related and may be preventable. Strategies that have been successful in preventing nosocomial device-related bacteremia should be adapted to the outpatient setting.

Introduction

Over 250,000 patients in the United States develop bacteremia or fungemia each year, with an associated mortality of 20 to 50% per episode Reimer et al 1997, Weinstein et al 1983a, Weinstein et al 1997. Septicemia is now the twelfth leading cause of death in the United States (Anonymous, 1998). Though many recent studies of nosocomial bacteremia have been reported, there are limited data focusing on community-acquired bacteremia (Mylotte et al., 2001).

Given the morbidity, mortality, and economic consequences of community-acquired bacteremia, we decided to better describe this important clinical problem. We thus provide a detailed and comprehensive analysis of community-acquired bacteremia occurring at a single institution over a recent four-year period. Our objectives in studying community-acquired bacteremia were to: 1) describe their epidemiologic and microbiologic characteristics; 2) determine the crude mortality and investigate the effect of selected factors on mortality; and 3) identify independent predictors of mortality.

Section snippets

Setting

This prospective study was conducted at the Seattle Division of the Veterans Affairs Puget Sound Healthcare System (VAPSHS) from January 1, 1994 to December 31, 1997. The VAPSHS is a 250-bed teaching hospital in Seattle, Washington, affiliated with the University of Washington School of Medicine.

Methods

We extracted data on all episodes of community-acquired bacteremia and fungemia occurring among patients admitted to the Seattle Division of the VAPSHS during the study period. All positive blood

Epidemiology

During the four-year study period, 387 episodes of community-acquired bacteremia were documented in 334 patients. The mean age of patients with community-acquired bacteremia was 62 years (range, 21–100), and the median length of hospital stay was nine days (range, 1–300). Comorbid conditions were frequent; 22% of episodes occurred in patients with diabetes mellitus, 21% in patients with renal failure, 21% in patients with a malignancy, and 13% in patients with COPD. In addition, 10% of episodes

Discussion

In our study of community-acquired bacteremias among patients admitted to a single institution over a four-year period, S. aureus was the leading pathogen and caused almost one-quarter of episodes. These findings are consistent with those of Weinstein and colleagues in a recent review (Weinstein et al., 1997), but differ from the results of their earlier study in 1975–77 (Weinstein et al., 1983a). At that time, the leading pathogens were E. coli and S. pneumoniae, with S. aureus identified as

Acknowledgments

We are indebted to Larry G. Carlson, MS, and Paul Baker, ARNP, for data support, and to the VA Epidemiologic Research and Information Center (ERIC), Seattle, for providing overall logistic support. This project was supported by a Department of Veterans Affairs research grant (EPP-97–015) awarded to Drs. Lipsky and Saint.

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