Rapid molecular testing for Staphylococcus aureus bacteraemia improves clinical management

TY - JOUR

T1 - Rapid molecular testing for Staphylococcus aureus bacteraemia improves clinical management

AU - McHugh, Martin P.

AU - Parcell, Benjamin J.

AU - MacKenzie, Fiona M.

AU - Templeton, Kate E.

N1 - This work was fund the Scottish Government HAI Policy Unit. , (Award NA)

PY - 2020

Y1 - 2020

N2 - Introduction: Staphylococcus aureus bacteraemia (SAB) causes significant morbidity and mortality. Standard diagnostic methods require 24-48 h to provide results, during which time management is guideline-based and may be suboptimal.Aim: Evaluate the impact of rapid molecular detection of S. aureus in positive blood culture bottle fluid on patient management.Methodology: Samples were tested prospectively at two clinical centres. Positive blood cultures with Gram-positive cocci in clusters on microscopy were tested with the Xpert MRSA/SA blood culture assay (Cepheid), as well as standard culture-based identification and antimicrobial sensitivity tests. Results were passed to clinical microbiologists in real time and used for patient management.Results: Of 264 blood cultures tested (184 and 80 from each centre), S. aureus was grown from 39 (14.8 %) with one identified as methicillin-resistant S. aureus; all Xpert results agreed with culture results. Median turnaround time from culture flagging positive to result reporting for Xpert was 1.7 h, compared to 25.7 h for species identification by culture. Xpert results allowed early changes to management in 40 (16.8 %) patients, with Xpert positive patients starting specific therapy for SAB and Xpert negative patients stopping or avoiding empiric antimicrobials for SAB.Conclusion: Rapid and accurate detection of S. aureus with the Xpert MRSA/SA BC assay in positive blood culture bottles allowed earlier targeted patient management. Negative Xpert results are suggestive of coagulase negative staphylococci, allowing de-escalation of antimicrobial therapy if clinically appropriate.

AB - Introduction: Staphylococcus aureus bacteraemia (SAB) causes significant morbidity and mortality. Standard diagnostic methods require 24-48 h to provide results, during which time management is guideline-based and may be suboptimal.Aim: Evaluate the impact of rapid molecular detection of S. aureus in positive blood culture bottle fluid on patient management.Methodology: Samples were tested prospectively at two clinical centres. Positive blood cultures with Gram-positive cocci in clusters on microscopy were tested with the Xpert MRSA/SA blood culture assay (Cepheid), as well as standard culture-based identification and antimicrobial sensitivity tests. Results were passed to clinical microbiologists in real time and used for patient management.Results: Of 264 blood cultures tested (184 and 80 from each centre), S. aureus was grown from 39 (14.8 %) with one identified as methicillin-resistant S. aureus; all Xpert results agreed with culture results. Median turnaround time from culture flagging positive to result reporting for Xpert was 1.7 h, compared to 25.7 h for species identification by culture. Xpert results allowed early changes to management in 40 (16.8 %) patients, with Xpert positive patients starting specific therapy for SAB and Xpert negative patients stopping or avoiding empiric antimicrobials for SAB.Conclusion: Rapid and accurate detection of S. aureus with the Xpert MRSA/SA BC assay in positive blood culture bottles allowed earlier targeted patient management. Negative Xpert results are suggestive of coagulase negative staphylococci, allowing de-escalation of antimicrobial therapy if clinically appropriate.

KW - Staphylococcus aureus

KW - bacteraemia

KW - Xpert

KW - rapid diagnosis

KW - antimicrobial stewardship.

UR - https://www.scopus.com/pages/publications/85085264051

U2 - 10.1099/jmm.0.001171

DO - 10.1099/jmm.0.001171

M3 - Article

C2 - 32141812

SN - 0022-2615

VL - 69

SP - 552

EP - 557

JO - Journal of Medical Microbiology

JF - Journal of Medical Microbiology

IS - 4

ER -