Clinical significance of potential contaminants in blood cultures among patients in a medical center

Ching Chi Lee, Wei Jeng Lin, Hsin-I Shih, Chi Jung Wu, Po-Lin Chen, Hsin Chun Lee, Nan-Yao Lee, Chia-Ming Chang, Li Rong Wang, Wen-Chien Ko

Research output: Contribution to journalArticle

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Abstract

Background and Purpose: Blood culture is important for the diagnosis of sepsis, but it is sometimes difficult to differentiate true bacteremia from pseudobacteremia. This study proposed clinical criteria and evaluated the role of repeat blood cultures in assessing the clinical significance of potential contaminants in blood cultures (PCBCs). Methods: From February to May in 2004 (prospective study) and 2003 (retrospective study), adult patients with growth of coagulase-negative staphylococci, Bacillus spp., Micrococcus spp., Propionibacterium spp., Gram-positive bacilli, or Clostridium perfringens, collectively referred to as "PCBCs", in at least 1 set of blood cultures in a medical center were included. The demographic and clinical data of patients with PCBCs were collected, and proposed clinical criteria for true bloodstream infections were used to evaluate their clinical outcome. Also, the potential role of repeating blood cultures to differentiate true bacteremia from pseudobacteremia was evaluated. Results: There were 212 cases with 214 PCBCs, of which coagulase-negative staphylococci predominated (182 isolates, 85.0%). The overall contamination rate was 83.9% (178/212). Repeating 2 sets of blood cultures might be useful in the clinical differentiation of true bacteremia and pseudobacteremia, since the contamination rate of patients with potential contaminants in 1 set of blood cultures declined from 95% to 87% (p=0.04) with such a strategy. Those with true bloodstream infections had a significantly higher all-cause mortality rate at 14 days than those with pseudobacteremia (23.8% vs 7.3%, p=0.028), suggesting the validity of the clinical criteria. Of the 178 cases with pseudobacteremia, 73 (41.0%) were unnecessarily treated by systemic antibiotics, of which glycopeptides accounted for 20.0%. For these cases, antimicrobial therapy offered no survival benefit. Conclusions: In an era of increasing glycopeptide resistance among Gram-positive cocci, clinical strategies for the early diagnosis of pseudobacteremia in cases with PCBCs are urgently required, in order to avoid the unnecessary use of glycopeptides. The proposed criteria and repeat blood culturing seem to be useful in the assessment of the clinical significance of PCBCs, and for reduction of the inappropriate use of glycopeptides.

Original languageEnglish
Pages (from-to)438-444
Number of pages7
JournalJournal of Microbiology, Immunology and Infection
Volume40
Issue number5
Publication statusPublished - 2007 Oct

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Glycopeptides
Bacteremia
Coagulase
Staphylococcus
Bacillus
Blood Culture
Propionibacterium
Micrococcus
Gram-Positive Cocci
Clostridium perfringens
Infection
Early Diagnosis
Sepsis
Retrospective Studies
Demography
Prospective Studies
Anti-Bacterial Agents
Survival
Mortality
Growth

All Science Journal Classification (ASJC) codes

  • Microbiology (medical)
  • Immunology and Allergy
  • Immunology and Microbiology(all)

Cite this

@article{b4130acd1f25481187f5b4456517486d,
title = "Clinical significance of potential contaminants in blood cultures among patients in a medical center",
abstract = "Background and Purpose: Blood culture is important for the diagnosis of sepsis, but it is sometimes difficult to differentiate true bacteremia from pseudobacteremia. This study proposed clinical criteria and evaluated the role of repeat blood cultures in assessing the clinical significance of potential contaminants in blood cultures (PCBCs). Methods: From February to May in 2004 (prospective study) and 2003 (retrospective study), adult patients with growth of coagulase-negative staphylococci, Bacillus spp., Micrococcus spp., Propionibacterium spp., Gram-positive bacilli, or Clostridium perfringens, collectively referred to as {"}PCBCs{"}, in at least 1 set of blood cultures in a medical center were included. The demographic and clinical data of patients with PCBCs were collected, and proposed clinical criteria for true bloodstream infections were used to evaluate their clinical outcome. Also, the potential role of repeating blood cultures to differentiate true bacteremia from pseudobacteremia was evaluated. Results: There were 212 cases with 214 PCBCs, of which coagulase-negative staphylococci predominated (182 isolates, 85.0{\%}). The overall contamination rate was 83.9{\%} (178/212). Repeating 2 sets of blood cultures might be useful in the clinical differentiation of true bacteremia and pseudobacteremia, since the contamination rate of patients with potential contaminants in 1 set of blood cultures declined from 95{\%} to 87{\%} (p=0.04) with such a strategy. Those with true bloodstream infections had a significantly higher all-cause mortality rate at 14 days than those with pseudobacteremia (23.8{\%} vs 7.3{\%}, p=0.028), suggesting the validity of the clinical criteria. Of the 178 cases with pseudobacteremia, 73 (41.0{\%}) were unnecessarily treated by systemic antibiotics, of which glycopeptides accounted for 20.0{\%}. For these cases, antimicrobial therapy offered no survival benefit. Conclusions: In an era of increasing glycopeptide resistance among Gram-positive cocci, clinical strategies for the early diagnosis of pseudobacteremia in cases with PCBCs are urgently required, in order to avoid the unnecessary use of glycopeptides. The proposed criteria and repeat blood culturing seem to be useful in the assessment of the clinical significance of PCBCs, and for reduction of the inappropriate use of glycopeptides.",
author = "Lee, {Ching Chi} and Lin, {Wei Jeng} and Hsin-I Shih and Wu, {Chi Jung} and Po-Lin Chen and Lee, {Hsin Chun} and Nan-Yao Lee and Chia-Ming Chang and Wang, {Li Rong} and Wen-Chien Ko",
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Clinical significance of potential contaminants in blood cultures among patients in a medical center. / Lee, Ching Chi; Lin, Wei Jeng; Shih, Hsin-I; Wu, Chi Jung; Chen, Po-Lin; Lee, Hsin Chun; Lee, Nan-Yao; Chang, Chia-Ming; Wang, Li Rong; Ko, Wen-Chien.

In: Journal of Microbiology, Immunology and Infection, Vol. 40, No. 5, 10.2007, p. 438-444.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Clinical significance of potential contaminants in blood cultures among patients in a medical center

AU - Lee, Ching Chi

AU - Lin, Wei Jeng

AU - Shih, Hsin-I

AU - Wu, Chi Jung

AU - Chen, Po-Lin

AU - Lee, Hsin Chun

AU - Lee, Nan-Yao

AU - Chang, Chia-Ming

AU - Wang, Li Rong

AU - Ko, Wen-Chien

PY - 2007/10

Y1 - 2007/10

N2 - Background and Purpose: Blood culture is important for the diagnosis of sepsis, but it is sometimes difficult to differentiate true bacteremia from pseudobacteremia. This study proposed clinical criteria and evaluated the role of repeat blood cultures in assessing the clinical significance of potential contaminants in blood cultures (PCBCs). Methods: From February to May in 2004 (prospective study) and 2003 (retrospective study), adult patients with growth of coagulase-negative staphylococci, Bacillus spp., Micrococcus spp., Propionibacterium spp., Gram-positive bacilli, or Clostridium perfringens, collectively referred to as "PCBCs", in at least 1 set of blood cultures in a medical center were included. The demographic and clinical data of patients with PCBCs were collected, and proposed clinical criteria for true bloodstream infections were used to evaluate their clinical outcome. Also, the potential role of repeating blood cultures to differentiate true bacteremia from pseudobacteremia was evaluated. Results: There were 212 cases with 214 PCBCs, of which coagulase-negative staphylococci predominated (182 isolates, 85.0%). The overall contamination rate was 83.9% (178/212). Repeating 2 sets of blood cultures might be useful in the clinical differentiation of true bacteremia and pseudobacteremia, since the contamination rate of patients with potential contaminants in 1 set of blood cultures declined from 95% to 87% (p=0.04) with such a strategy. Those with true bloodstream infections had a significantly higher all-cause mortality rate at 14 days than those with pseudobacteremia (23.8% vs 7.3%, p=0.028), suggesting the validity of the clinical criteria. Of the 178 cases with pseudobacteremia, 73 (41.0%) were unnecessarily treated by systemic antibiotics, of which glycopeptides accounted for 20.0%. For these cases, antimicrobial therapy offered no survival benefit. Conclusions: In an era of increasing glycopeptide resistance among Gram-positive cocci, clinical strategies for the early diagnosis of pseudobacteremia in cases with PCBCs are urgently required, in order to avoid the unnecessary use of glycopeptides. The proposed criteria and repeat blood culturing seem to be useful in the assessment of the clinical significance of PCBCs, and for reduction of the inappropriate use of glycopeptides.

AB - Background and Purpose: Blood culture is important for the diagnosis of sepsis, but it is sometimes difficult to differentiate true bacteremia from pseudobacteremia. This study proposed clinical criteria and evaluated the role of repeat blood cultures in assessing the clinical significance of potential contaminants in blood cultures (PCBCs). Methods: From February to May in 2004 (prospective study) and 2003 (retrospective study), adult patients with growth of coagulase-negative staphylococci, Bacillus spp., Micrococcus spp., Propionibacterium spp., Gram-positive bacilli, or Clostridium perfringens, collectively referred to as "PCBCs", in at least 1 set of blood cultures in a medical center were included. The demographic and clinical data of patients with PCBCs were collected, and proposed clinical criteria for true bloodstream infections were used to evaluate their clinical outcome. Also, the potential role of repeating blood cultures to differentiate true bacteremia from pseudobacteremia was evaluated. Results: There were 212 cases with 214 PCBCs, of which coagulase-negative staphylococci predominated (182 isolates, 85.0%). The overall contamination rate was 83.9% (178/212). Repeating 2 sets of blood cultures might be useful in the clinical differentiation of true bacteremia and pseudobacteremia, since the contamination rate of patients with potential contaminants in 1 set of blood cultures declined from 95% to 87% (p=0.04) with such a strategy. Those with true bloodstream infections had a significantly higher all-cause mortality rate at 14 days than those with pseudobacteremia (23.8% vs 7.3%, p=0.028), suggesting the validity of the clinical criteria. Of the 178 cases with pseudobacteremia, 73 (41.0%) were unnecessarily treated by systemic antibiotics, of which glycopeptides accounted for 20.0%. For these cases, antimicrobial therapy offered no survival benefit. Conclusions: In an era of increasing glycopeptide resistance among Gram-positive cocci, clinical strategies for the early diagnosis of pseudobacteremia in cases with PCBCs are urgently required, in order to avoid the unnecessary use of glycopeptides. The proposed criteria and repeat blood culturing seem to be useful in the assessment of the clinical significance of PCBCs, and for reduction of the inappropriate use of glycopeptides.

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