Infective Endocarditis Due to Species: Clinical Features and Antibiotic Resistance

Background: species are often dismissed as contaminants in blood cultures, but they can also cause infective endocarditis (IE), which is a severe condition. Antibiotic resistance of corynebacteria is increasing making treatment challenging. Reports on IE caused by species are scarce and more knowledge is needed.

Methods: Cases of IE caused by species were identified through the Swedish Registry of Infective Endocarditis. Isolates were collected for species redetermination by matrix-assisted laser desorption ionization-time of flight and for antibiotic susceptibility testing using Etests.

Results: Thirty episodes of IE due to species were identified between 2008 and 2017. The median age of patients was 71 years (interquartile range, 60-76) and 77% were male. (n = 11) was the most common IE causing pathogen followed by (n = 5). Surgery was performed in 50% and in-hospital mortality rate was 13%. Patients with IE caused by species were significantly more likely to have prosthetic valve endocarditis (70%), compared with patients with IE due to or non-beta-hemolytic streptococci (14% and 26%, respectively) ( < .0001). Vancomycin was active towards all isolates, whereas resistance towards penicillin G was common.

Conclusions: species cause IE, where prosthetic valves are mainly affected and surgery is often performed. is an important causative agent of IE within the genus. Antibiotic resistance of corynebacteria is relatively common but resistance towards vancomycin could not be detected in vitro.