16S rRNA Metabarcoding Used to Identify the Etiology of Infective Endocarditis Agents.

Streptococcus was the most frequently identified major microorganism in native cardiac valves affected by infective endocarditis.

• Streptococcus was present in 40% of all valves studied
• Major microorganisms were defined as those with a portion over 5% from all identified bacterial agents in the sample
• The study material involved 20 native cardiac valve samples from 16 patients

Sphingomonas and Pseudomonas were identified as major bacterial agents each present in 35% of the studied cardiac valves.

• Both Sphingomonas and Pseudomonas were found in 35% of all valves studied
• These organisms are opportunistic pathogens not typically associated with infective endocarditis in routine diagnostics
• Detection required metabarcoding rather than standard blood culture methods

Roseateles and Phyllobacterium were each identified as major bacterial agents in 25% of the studied cardiac valves.

• Both Roseateles and Phyllobacterium were found in 25% of all valves studied
• These represent uncommon or rare infective endocarditis pathogens
• Major microorganism status required greater than 5% representation from all identified bacterial agents in the sample

Enterococcus was identified as a major bacterial agent in 15% of the studied cardiac valves.

• Enterococcus was present in 15% of all valves studied
• Enterococcus is a known causative agent of infective endocarditis detectable by conventional methods
• Study included 20 native cardiac valve samples from 16 patients

Rare bacterial agents including Ralstonia pickettii, Bacillus, and Klebsiella representatives were also detected in the studied cardiac valves.

• Ralstonia pickettii was identified as a rare finding in the studied valves
• Representatives of Bacillus and Klebsiella were also found in rare cases
• These organisms were present below the 5% threshold that defined major microorganisms

16S rRNA metabarcoding demonstrated efficiency in identifying bacterial agents compared to routine noninvasive diagnostic methods.

• Sequencing was performed on a MiSeq sequenator (Illumina, USA) using MiSeq Reagent Kit v3 (2×300 bp)
• Sequencing was carried out at the Center for Collective Use 'Genomics' at the Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences
• Native cardiac valves isolated from patients with infective endocarditis were characterized by numerous opportunistic pathogenic bacteria in negative blood cultures
• The method identified pathogens in cases where conventional blood culture methods yielded negative results