Proof of Concept Evaluation of a New Diagnostic POCT Device for Culture- Independent Microbiological Diagnosis of Infective Endocarditis

Abstract

Introduction: Accurate and fast microbiological diagnosis of infective endocarditis (IE) is of vital importance for patient outcome. Material & Methods: Forty culture-negative heart valves were evaluated with a new POCT multiplex-PCR cartridge (Unyvero™, Curetis AG, Holzgerlingen, Germany), advertised to detect several Gram positive/­negative bacteria and fungi, together with several antibiotic resistance genes. Those POCT results were compared to conventional 16S rDNA PCR/sequencing results. Results: POCT multiplex-PCR was positive in 13 cases [Staphylococcus aureus (n=5), Enterococcus spp. / E. faecalis (n=5), ConS (n=1), Granulicatella adjacens (n=1), Abiotrophia adjacens (n=1)]. Antibiotic resistances were found in 44 specimens, from which 2 specimens were without any pathogen identification. 16S rDNA PCR was positive in 20 cases. Consecutive sequencing identified those as Staphylococcus spp. (n=6), Enterococcus faecalis (n=4), Streptococcus spp. (n=4), Leifsonia shinshuensis (n=1), Granulicatella elegans / G. adjacens (n=2), Abiotrophia adjacens (n=1). One case was positive in 16S PCR without any reliable signal in sequencing. When comparing both methods, identification was consistent in 9 cases and divergent in other 9 cases. Discussion: This POCT cartridge is easy to integrate into the daily microbiology laboratory work flow, and is less laborious than 16S sequencing PCR. For the application in routine IE diagnosis, the system needs to be optimized to include targets for viridans streptococci and HACEK group. In addition, problems with invalid resistance and pathogen target detection need to be fixed by the producer. Conclusion: The analyzed POCT system might be a future diagnostic tool for IE detection following assay optimization.