Assessment of a Multiplex LAMP Assay (Eazyplex® CSF Direct M) for Rapid Molecular Diagnosis of Bacterial Meningitis: Accuracy and Pitfalls

Abstract

Background: Automated molecular panels are attractive tools for improving early meningitis diagnosis. This study assessed the Eazyplex® CSF direct M panel (EP), a multiplex real-time Loop-Mediated Isothermal Amplification assay. Methods: From December 2016 to December 2019, cerebrospinal fluid (CSF) samples were routinely tested with the EP V1.0. CSF parameters and microbiological and clinical data were retrospectively collected. Results: Out of 230 CSF samples, the EP yielded positive, negative, and invalid results for 32 (13.9%) (16 N. meningitidis, nine S. pneumoniae, two S. agalactiae, two E. coli, two H. influenzae, one L. monocytogenes), 182 (79.1%), and 16 (7%) samples, respectively. Among the positive samples, 14 (44%) remained negative in culture (antibiotic therapy before lumbar puncture (n = 11), meningococcal meningitis (n = 3)). High CSF protein concentrations and cellularity were associated with LAMP inhibition, counteracted by centrifugation. The automated software yielded 13 false positive and five false negative results. Amplification curve analysis was necessary and enabled the attainment of positive (PPA) and negative percentage agreement and positive and negative predictive values of 91.4%, 100%, 100%, and 98.3%. Three false negative results remained (two E. coli and one N. meningitidis). E. coli presented the poorest PPA (50%). Conclusion: This work confirms the strong performance of the EP, of particular interest in cases of antibiotic therapy before lumbar puncture.

Loop-Mediated Isothermal Amplification Assays for the Detection of Antimicrobial Resistance Elements inVibrio cholerae

“…For example, molecular diagnostics such as polymerase chain reaction (PCR) and quantitative PCR (qPCR) assays quickly and reliably amplify target genetic material to detect the presence of targeted pathogenic organisms, but field usage is limited since they require bulky or expensive thermocycler instruments. Recently, loop-mediated isothermal amplification (LAMP) assays have become popular for bacterial and viral sample analyses; they are quicker than PCR, do not require expensive equipment, and provide a visual colorimetric readout of positive detection (8)(9)(10)(11)(12). However, the use of LAMP assays faces challenges that slow adoption and limit their usefulness.…”