Comparative evaluation of Biofire Joint Infection Panel, Sepsitest 16S/18S rDNA PCR, and culture to identify microorganisms in explanted heart valves

Infective endocarditis (IE) is a major life-threatening disease. However, the inability to identify the causative pathogen using conventional microbiological cultures jeopardizes the choice of optimal antibiotic therapy. Culture-independent molecular techniques for pathogen detection may overcome this challenge. Here, two molecular tests (16S/18S rDNA assay SepsiTest, Molzym, Germany; Biofire Joint Infection Panel BJP, bioMérieux, Marcy l'Étoile, France) were analyzed for their ability to detect pathogens in a series of 100 explanted heart valves. In total, at least one pathogen was detected in 67/100 specimens by one or more methods, and 33/100 specimens were negative in all three assays. Overall, valve-culture had an inferior sensitivity (39.4%), compared to 16S/18S rDNA PCR (90.9%) and the BJP (83.1% all organisms, 98.2% on-panel organisms only). In culture-negative cases, 35 and 32 additional pathogens were identified by 16S/18S rDNA PCR and BJP, respectively. In five culture- and 16S/18S rDNA assay-negative cases, BJP identified correctly additional pathogens. False-positive results were observed in one (16S/18S rDNA PCR) and two (BJP) cases, respectively. In conclusion, both culture-independent assays proved to be reliable and increased the diagnostic yield compared to culture. In general, false negatives (i.e., off-panel pathogens in BJP) and false positives require careful clinical evaluation of results from culture-independent techniques. Diagnostic stewardship is essential to guide the optimal use of molecular techniques in the work-up of infective endocarditis.IMPORTANCEInfective endocarditis (IE) therapy must be guided by the identification of the causative pathogen. Microbiological cultures, however, remain negative in a significant number of cases, jeopardizing the choice of optimal anti-infective treatment. This study evaluated the ability of two independent molecular tests (16/18S rDNA PCR, syndromic panel PCR Biofire JI panel) to overcome limitations of conventional microbiological approaches to detect microorganisms from explanted heart valve tissues. Both assays proved to have a greater sensitivity compared to conventional culture, and PCR and BJP identified a pathogen in 35 and 32 out of 74 culture negative IE cases, additional pathogens, respectively. The study highlights the great importance of culture-independent approaches to pathogen detection in IE and guides the choice of the optimal assay using diagnostic stewardship interventions.