Evaluation of the eazyplex MRSA assay for the rapid detection of Staphylococcus aureus in pleural and synovial fluid

Abstract

Objective: Loop-mediated isothermal amplification (LAMP) is a simple and sensitive technique for rapid microbiological diagnosis. The aim of this study was to evaluate the analytical and diagnostic performance of the LAMP eazyplex MRSA test for the direct detection and differentiation of methicillin-susceptible (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) in synovial/pleural fluid. Methods: Analytical validation included the determination of the limit of detection (LoD) and analytical specificity of the eazyplex MRSA test. A diagnostic evaluation of the eazyplex test against bacterial culture was performed on routine pleural/synovial samples collected prospectively from patients aged less than 18 years with complicated pneumonia with empyema or arthritis admitted to the Children’s Hospital Sant Joan de Déu in Barcelona, Spain, between April 2015 and May 2016. Results: The new system appropriately detected a quality control panel of clinical samples with DNA of MSSA, MRSA, and other pathogens. The LoD was established at 6.4 × 103 CFU/ml for S. aureus and 1.0 × 104 CFU/ml for MRSA. Diagnostic validation of the eazyplex MRSA assay was performed on 51 prospective clinical invasive samples, resulting in sensitivity and specificity values of 83.3% and 97.8%, respectively, for S. aureus detection. The mean turnaround time was 70 min. Conclusions: The eazyplex MRSA assay was found to be a useful test for the rapid detection of S. aureus in invasive samples such as pleural/synovial fluid.

Keywords

• MSSA
• MRSA
• Pleural and synovial fluid
• eazyplex MRSA
• Performance evaluation