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Reemergence of gram-negative health care-associated bloodstream infections
Svenja J Albrecht1, Neil O Fishman, Jennifer Kitchen
1Division of Infectious Diseases, Department of Medicine, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, 423 Guardian Drive, Philadelphia, PA 19104, USA.
Background:
Primary health care-associated bloodstream infections (PHA-BSIs) affect as many as 350 000 patients in the United States annually. Whereas gram-negative organisms were the leading cause before the 1970s, gram-positive organisms have been the predominant microbial isolates since then.
Methods:
We identified all PHA-BSIs among adult inpatients in a 625-bed quaternary care hospital from January 1, 1996, through December 31, 2003, and evaluated trends in the microbial etiology, geographic distribution within the institution, and antimicrobial susceptibilities.
Results:
A total of 3662 PHA-BSIs caused by 4349 bacterial and fungal isolates were identified. From 1999 to 2003, the proportion of PHA-BSIs due to gram-negative organisms increased from 15.9% to 24.1% (P<.001 for trend). This trend was not significantly different across various units of the hospital, and no specific gram-negative species contributed disproportionately to the increase. With few exceptions, there were no significant increases in antimicrobial resistance. The increase in gram-negative organisms was accompanied by a decline in the proportion of PHA-BSIs from coagulase-negative staphylococci (from 33.5% in 1999 to 29.9% in 2003, P = .007) and from Staphylococcus aureus (from 18.8% in 1999 to 11.8% in 2003, P = .004). The proportion of PHA-BSIs from Candida species almost doubled from 5.8% in 1999 to 11.3% in 2003 (P = .002).
Conclusions:
To our knowledge, this is the first US study to report a reemergence of gram-negative organisms as a cause of PHA-BSIs. This finding does not seem to be related to changes in specific gram-negative organisms or to antimicrobial resistance. If this trend continues, it will have important implications for the management of bloodstream infections.
Insights
Gram-negative organisms are reemerging as a significant cause of primary health care-associated bloodstream infections (PHA-BSIs) in US hospitals. This trend, observed from 1999-2003, indicates a shift from gram-positive dominance and requires attention for infection management.
Area of Science:
- Infectious Diseases
- Clinical Microbiology
- Hospital Epidemiology
Background:
- Primary health care-associated bloodstream infections (PHA-BSIs) are a major concern, affecting numerous patients annually in the US.
- Historically, gram-negative organisms predominated before the 1970s, with gram-positive organisms becoming more prevalent thereafter.
Purpose of the Study:
- To investigate the trends in microbial etiology, geographic distribution, and antimicrobial susceptibilities of PHA-BSIs in a large quaternary care hospital.
- To identify shifts in the causative agents of PHA-BSIs over an eight-year period.
Main Methods:
- Retrospective analysis of all PHA-BSIs in adult inpatients from January 1996 to December 2003.
- Evaluation of bacterial and fungal isolates, including species identification and antimicrobial susceptibility testing.
Main Results:
- A significant increase in PHA-BSIs caused by gram-negative organisms was observed from 15.9% (1999) to 24.1% (2003).
- This rise in gram-negative infections coincided with a decrease in infections caused by coagulase-negative staphylococci and Staphylococcus aureus.
- The proportion of PHA-BSIs due to Candida species nearly doubled during the study period.
Conclusions:
- This study reports the first documented reemergence of gram-negative organisms as a leading cause of PHA-BSIs in the US.
- The observed trend was not linked to specific gram-negative species or increased antimicrobial resistance.
- The findings necessitate a reevaluation of strategies for managing bloodstream infections in healthcare settings.
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