Can the Xpert MRSA/SA BC assay be used as an antimicrobial stewardship tool? A prospective assay validation and descriptive impact assessment study in a South African setting.

Publisher: BioMed Central Country of Publication: England NLM ID: 100968551 Publication Model: Electronic Cited Medium: Internet ISSN: 1471-2334 (Electronic) Linking ISSN: 14712334 NLM ISO Abbreviation: BMC Infect Dis Subsets: MEDLINE

Original Publication: London : BioMed Central, [2001-

Anti-Bacterial Agents/*therapeutic use ; Antimicrobial Stewardship/*methods ; Methicillin/*therapeutic use ; Molecular Diagnostic Techniques/*methods ; Staphylococcal Infections/*drug therapy; Adult ; Anti-Bacterial Agents/pharmacology ; Bacteremia/diagnosis ; Bacteremia/drug therapy ; Bacteremia/microbiology ; Female ; Humans ; Infant ; Infant, Newborn ; Male ; Methicillin/pharmacology ; Methicillin-Resistant Staphylococcus aureus/genetics ; Methicillin-Resistant Staphylococcus aureus/isolation & purification ; Middle Aged ; Prospective Studies ; South Africa ; Staphylococcal Infections/diagnosis ; Staphylococcal Infections/microbiology ; Staphylococcus/genetics ; Staphylococcus/isolation & purification ; Staphylococcus aureus/genetics ; Staphylococcus aureus/isolation & purification ; Time Factors

Background: Positive blood cultures showing Gram positive cocci in clusters signifies either Staphylococcus aureus or the less-virulent coagulase-negative staphylococci. Rapid identification and methicillin susceptibility determination with the Xpert MRSA/SA BC assay can improve management of S. aureus bloodstream infection and reduce inappropriate antibiotic use.
Methods: We prospectively evaluated the Xpert MRSA/SA BC assay in comparison with culture, on samples referred to our laboratory in the Western Cape, South Africa. We interviewed attending clinicians upon culture result availability, to assess antibiotic choices and estimate potential impact of the assay.
Results: Of the 231 samples included, there was 100% concordance between the Xpert MRSA/SA BC assay and culture (methicillin-resistant S. aureus 15/15, methicillin-susceptible S. aureus 42/42, coagulase-negative staphylococci 170/170). Time to final result could be reduced by approximately 30 h with the assay. Of the 178 patients with adequate antibiotic history, optimisation of antistaphylococcal therapy could have occurred more than 1 day sooner in 68.9% with S. aureus bloodstream infection (31/45, 95% CI 53.2-81.4%). Six of the 11 patients with methicillin-resistant S. aureus bloodstream infection (54.5%) could have received anti-MRSA cover sooner. Fifty-four days of antibiotic therapy could have been spared, equating to 0.3 days (95% CI, 0.2-0.4) saved per patient, driven by broad-spectrum beta-lactams (32 days, in 18.0% of the cohort).
Conclusion: This assay has potential as an antimicrobial stewardship tool; costing and impact on clinical outcome in patients with S. aureus bloodstream infection should be assessed.

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Keywords: Antimicrobial stewardship; Staphylococcal bloodstream infection; Staphylococcus aureus; Xpert MRSA/SA BC

0 (Anti-Bacterial Agents)
Q91FH1328A (Methicillin)

Date Created: 20210216 Date Completed: 20210315 Latest Revision: 20240330

20250114

PMC7885373

10.1186/s12879-021-05857-7

33588782