Abstract
Infective endocarditis (IE) is a severe and life-threatening disease. Identification of infectious etiology is essential for establishing the appropriate antimicrobial treatment and decreasing mortality. The aim of this study was to explore the potential utility of metataxonomics for improving microbiological diagnosis of IE. Here, next-generation sequencing (NGS) of the V3–V4 region of the 16S rRNA gene was performed in 27 heart valve tissues (18 natives, 5 intravascular devices, and 4 prosthetics) from 27 patients diagnosed with IE (4 of them with negative blood cultures). Metataxonomics matched with conventional diagnostic techniques in 24/27 cases (88.9%). The same bacterial family was assigned to 24 cases; the same genus, to 23 cases; and the same species, to 13 cases. In 22 of them, the etiological agent was represented by percentages > 99% of the reads and in two cases, by ~70%. Staphylococcus aureus was detected in a previously microbiological undiagnosed patient. Thus, microbiological diagnosis with 16S rRNA gene targeted-NGS was possible in one more sample than using traditional techniques. The remaining two patients showed no coincidence between traditional and 16S rRNA gene-targeted NGS microbiological diagnoses. In addition, 16S rRNA gene-targeted NGS allowed us to suggest coinfections that were supported by clinical data in one patient, and minority records also verified mixed infections in three cases. In our series, metataxonomics was valid for the identification of the causative agents, although more studies are needed before implementation of 16S rRNA gene-targeted NGS for the diagnosis of IE.
Highlights
Infective endocarditis (IE) is defined as an infection of a native or prosthetic cardiac valve, endocardial surface, or indwelling cardiac device [1]
For instance, it is worth noting that findings obtained with traditional molecular techniques for patient IDs #17 and #18 were observed when metataxonomics was performed
The metataxonomic results from patient ID #17 showed high relative abundance of Streptococcus agalactiae (99.9%) and low relative abundance of Coxiellaceae (
Summary
Infective endocarditis (IE) is defined as an infection of a native or prosthetic cardiac valve, endocardial surface, or indwelling cardiac device [1]. Despite trends towards earlier diagnosis, pharmacotherapy, and surgical intervention, IE remains a major medical concern associated with high mortality and severe complications. It is essential to identify the causative agent(s) for optimal patient management and to guide treatment duration and antibiotic choice. Staphylococci and streptococci cause about 80% of cases of IE. Staphylococcus aureus is the most common etiologic agent, accounting for about 30% of cases, followed by oral streptococci (~20%), other streptococci (~10%), enterococci (~10%), and coagulase-negative staphylococci (~10%). The remaining causes of IE are mainly the HACEK group organisms (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella species), Coxiella burnetii, Bartonella spp., and Tropheryma whipplei. Fungi are a rare endocarditis cause (~2%), with Candida spp. being the most common etiological agents within this group. Polymicrobial infections are responsible for 1% of the cases [1,2,3]
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