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Determining the Significance of Coagulase-Negative Staphylococci Isolated From Blood Cultures at a Community Hospital A Role for Species and Strain Identification

Published online by Cambridge University Press:  02 January 2015

Soon-Duck Kim
Affiliation:
Hospital Infections Program, Centers for Disease Control and Prevention, Atlanta, Georgia Dekalb Medical Center, Decatur, Georgia
L. Clifford McDonald
Affiliation:
Hospital Infections Program, Centers for Disease Control and Prevention, Atlanta, Georgia Dekalb Medical Center, Decatur, Georgia
William R. Jarvis*
Affiliation:
Hospital Infections Program, Centers for Disease Control and Prevention, Atlanta, Georgia Dekalb Medical Center, Decatur, Georgia
Sigrid K. McAllister
Affiliation:
Hospital Infections Program, Centers for Disease Control and Prevention, Atlanta, Georgia Dekalb Medical Center, Decatur, Georgia
Robert Jerris
Affiliation:
Hospital Infections Program, Centers for Disease Control and Prevention, Atlanta, Georgia Dekalb Medical Center, Decatur, Georgia
Loretta A. Carson
Affiliation:
Hospital Infections Program, Centers for Disease Control and Prevention, Atlanta, Georgia Dekalb Medical Center, Decatur, Georgia
J. Michael Miller
Affiliation:
Hospital Infections Program, Centers for Disease Control and Prevention, Atlanta, Georgia Dekalb Medical Center, Decatur, Georgia
*
Hospital Infections Program (HIP), Centers for Disease Control and Prevention, 1600 Clifton Rd, MS E69, Atlanta, GA 30333

Abstract

Objectives:

To determine the degree to which species identification or strain relatedness assessment of successive blood culture isolates of coagulase-negative staphylococci (CNS) may improve the clinical diagnosis of bloodstream infection (BSI).

Setting:

400-bed community hospital.

Design:

Prospective laboratory survey during which all CNS blood culture isolates obtained between mid-August 1996 and mid-February 1997 (study period) were saved and later identified to the species level; selected isolates were genotyped using pulsed-field gel electrophoresis at the Centers for Disease Control and Prevention (CDC). Retrospective review of medical records of 37 patients with multiple cultures positive for CNS.

Results:

During the study period, 171 patients had blood cultures positive for CNS; 130 had single positive cultures and 41 had ≥2 positive cultures. Of these 41, 23 (62%) were from patients with signs and symptoms of BSI according to CDC surveillance definitions. Species identification and strain clonality of CNS isolates from patients with ≥2 positives revealed 3 (13%) of the 23 patients did not have a consistent CNS species, and another 3 (13%) did not have a consistent genotype in the ≥2 positive cultures, suggesting that CNS from these patients probably were contaminants. Thus, species identification and strain clonality assessment reduced by 27% the number of patients with BSI diagnosed based on the presence of symptoms and ≥2 positive blood cultures.

Conclusions:

Routine species identification and selected strain genotyping of CNS may reduce the misinterpretation of probable contaminants among patients with ≥2 positive blood cultures.

Type
Original Articles
Copyright
Copyright © The Society for Healthcare Epidemiology of America 2000

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