mariAST® utilizes the ArcDia™ TPX (Two-Photon Excitation) assay technique for highly sensitive and extremely specific direct pathogen detection and antimicrobial susceptibility testing (AST). The technique is widely described in scientific publications and field proven by the mariPOC® product line. It is a proprietary technology of the Finnish Company ArcDia International Ltd., the developer and manufacturer of mariPOC® and mariAST®. Thanks to ease of use, the platform can be used in decentralized testing and physician office labs (POLs) for delivering fast screening and diagnostic results. This enables optimizing patient management and hospital processes.
Direct detection of pathogen antigens takes place on polystyrene microparticles as the solid reaction phase. Laser-excited (λex=1064 nm) fluorescence of individual microparticles (specific fluorescence) is measured, separation-free, one at a time. The fluorescence brightness of the particles is in direct proportion to target concentration in the sample. The reagents and the antimicrobials are stored dried in test reaction wells.
Unlike in mariPOC® where typically the target pathogens are inactivated and disintegrated, in mariAST® the reaction environment supports bacterial growth. The more the bacteria grow, the more signal is generated, and the signal change is monitored in real-time. When the reaction is supplemented with an antimicrobial, only those bacteria resistant for the agent can grow and produce signal. The methodology is a fast version of golden standard broth microdilution (BMD) with the exception that whereas BMD requires isolated strains, mariAST® can go directly to clinical samples. This saves time.
Finally, sophisticated data reduction algorithms return the quantitative test result and perform autoverification.
High sensitivity and specificity
Thanks to the principle of culturing the bacteria and simultaneously monitoring the growth, mariAST® provides the ultimate sensitivity of one CFU per assay. In a typical product this corresponds to initial concentration of 50 CFU/ml. This level of sensitivity cannot be exceeded even with PCR based products. The specificity is similar to mariPOC® applications.
mariAST® is unique
A recent trend in microbiology is towards developing products for rapid phenotypic AST from positive blood culture bottles (sepsis). These methods, such as automated microscopy, are not suited for direct testing of samples containing commensal flora. Notably, sepsis AST, while of very high clinical importance, represents just a minor fraction of all AST applications.
Common infections are becoming untreatable due to the emergence of antimicrobial resistance (AMR). To diagnose and treat resistant infections, and to minimize emerging of resistance, the problem should be solved by decentralized rapid infection diagnostics combining both identification and resistance testing of pathogens. mariAST® is the only presented platform technically and economically suitable for phenotypic and rapid AST in decentralized settings.