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Determining the Clinical Significance of Coagulase-Negative Staphylococci Isolated From Blood Cultures

Published online by Cambridge University Press:  21 June 2016

Susan E. Beekmann ,
Daniel J. Diekema  and
Gary V. Doern
Susan E. Beekmann*
Affiliation:
Division of Medical Microbiology, Department of Pathology, University of Iowa College of Medicine, Iowa City, Iowa
Daniel J. Diekema
Affiliation:
Division of Infectious Diseases, Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, Iowa
Gary V. Doern
Affiliation:
Division of Medical Microbiology, Department of Pathology, University of Iowa College of Medicine, Iowa City, Iowa
*
University of Iowa, 265 MRC, Iowa City, IA 52242.[email protected]
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Abstract

Background and Objective:

Coagulase-negative staphylococci are both an important cause of nosocomial bloodstream infections and the most common contaminants of blood cultures. Judging the clinical significance of coagulase-negative staphylococci is vital but often difficult and can have a profound impact on an institution's bloodstream infection rates. Our objective was to develop an algorithm to assist in determining the clinical significance of coagulase-negative staphylococci.

Design:

A single experienced reviewer examined the medical records of 960 consecutive patients with positive blood cultures in a tertiary-care referral teaching hospital. Four hundred five of the cultures contained coagulase-negative staphylococci. A determination of clinical significance was made and the performances of various published algorithms that contained readily available clinical and laboratory data were compared.

Results:

Eighty-nine (22%) of the episodes were considered significant, whereas 316 were contaminants. Patients with bacteremia were significantly more likely to be neutropenic and exhibit signs of sepsis syndrome. The algorithm with the best combined sensitivity (62%) and specificity (91%) for determining the clinical significance of coagulase-negative staphylococci was defined as at least two blood cultures positive for coagulase-negative staphylococci within 5 days, or one positive blood culture plus clinical evidence of infection, which includes abnormal white blood cell count and temperature or blood pressure.

Conclusion:

Use of this algorithm could potentially reduce misclassification of nosocomial bloodstream infections and inappropriate use of vancomycin for positive blood cultures likely to represent contamination (Infect Control Hosp Epidemiol 2005;26:559-566).

Type
Original Articles
Information
Infection Control & Hospital Epidemiology , Volume 26 , Issue 6 , June 2005 , pp. 559 - 566
Copyright
Copyright © The Society for Healthcare Epidemiology of America 2005

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