Rapid Diagnosis of Staphylococcal Catheter-Related Bacteraemia in Direct Blood Samples by Real-Time PCR

PLoS One. 2016 Aug 29;11(8):e0161684. doi: 10.1371/journal.pone.0161684. eCollection 2016.

Abstract

Catheter-related bacteremia (CRB) is an important cause of morbidity and mortality among hospitalized patients, being staphylococci the main etiologic agents. The objective of this study was to assess the use of a PCR-based assay for detection of staphylococci directly from blood obtained through the catheter to diagnose CRB caused by these microorganisms and to perform a cost-effectiveness analysis. A total of 92 patients with suspected CRB were included in the study. Samples were obtained through the catheter. Paired blood cultures were processed by standard culture methods and 4 ml blood samples were processed by GeneXpert-MRSA assay for the detection of methicillin-susceptible (MSSA) or methicillin-resistant (MRSA) Staphylococcus aureus, and methicillin-resistant coagulase-negative staphylococci (MR-CoNS). Sixteen CRB caused by staphylococci were diagnosed among 92 suspected patients. GeneXpert detected 14 out of 16 cases (87.5%), including 4 MSSA and 10 MR-CoNS in approximately 1 hour after specimen receipt. The sensitivity and specificity of GeneXpert were 87.5% (CI 95%: 60.4-97.8) and 92.1% (CI 95%: 83-96.7), respectively, compared with standard culture methods. The sensitivity of GeneXpert for S. aureus was 100%. Regarding a cost-effectiveness analysis, the incremental cost of using GeneXpert was of 31.1€ per patient while the incremental cost-effectiveness ratio of GeneXpert compared with blood culture alones was about 180€ per life year gained. In conclusion, GeneXpert can be used directly with blood samples obtained through infected catheters to detect S. aureus and MR-CoNS in approximately 1h after sampling. In addition, it is cost-effective especially in areas with high prevalence of staphylococcal CRB.

MeSH terms

  • Bacteremia / diagnosis*
  • Bacteremia / etiology*
  • Bacteremia / microbiology
  • Catheters, Indwelling / microbiology*
  • Humans
  • Methicillin Resistance
  • Methicillin-Resistant Staphylococcus aureus / pathogenicity
  • Microbial Sensitivity Tests
  • Real-Time Polymerase Chain Reaction
  • Staphylococcal Infections / diagnosis*
  • Staphylococcal Infections / etiology*
  • Staphylococcal Infections / microbiology
  • Staphylococcus aureus / drug effects
  • Staphylococcus aureus / genetics
  • Staphylococcus aureus / pathogenicity*

Grant support

This study was funded by Cepheid (Sunnyvale, CA; USA). This study was supported by grant 2014SGR0653 from the Departament de Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya, by the Ministerio de Economía y Competitividad, Instituto de Salud Carlos III, co-financed by European Regional Development Fund (ERDF) “A Way to Achieve Europe,” the Spanish Network for Research in Infectious Diseases (REIPI RD12/0015). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We received fundings from Cepheid, however, this does not alter our adherence to PLOS ONE policies on sharing data and materials.