In silico resistance prediction of oral streptococci to recommended prophylactic antibiotics to prevent infective endocarditis upon dental procedures.

BACKGROUND: For over 70 years, guidelines have recommended antibiotics for infective endocarditis (IE) prophylaxis before dental procedures, focusing on oral streptococci. OBJECTIVES: Our in silico study aimed to evaluate the potential resistance of oral streptococci against prophylactic antibiotics used before invasive dental procedures to prevent IE. METHODS: The genomic assemblies and metadata of Streptococcus IE isolates were searched using specific terms in BioSample and RefSeq databases. Their antimicrobial resistance phenotypes for 91 drugs belonging to 22 different classes were predicted with ResFinder and analysed regarding the recommended IE dental prophylactic antibiotics, focusing on the oral streptococci assemblies. RESULTS: Among the 258 Streptococcus isolates dating from 1935 to 2021 from 12 countries, 79.46% were classified as oral streptococci, and 38.37% of the 258 assemblies carried resistance genes to at least one antimicrobial. Seven isolates carried the transposon Tn6331, which can confer resistance to aminoglycosides, macrolides, lincosamides, streptogramins and tetracyclines. Within the oral Streptococcus strains, none carried resistance genes to amoxicillin, but potential resistance to azithromycin (24.88%) and doxycycline (16.59%) was observed. CONCLUSIONS: Our in silico study showed that none of the oral Streptococcus assemblies from IE carried resistance genes to the primary regimen recommended for IE prophylaxis following invasive dental procedures. However, several assemblies were potentially resistant to alternative prophylactic regimens for patients allergic to penicillin or ampicillin.