Infective endocarditis caused by Gemella - a retrospective registry-based study.

Purpose: Infective endocarditis (IE) is diagnosed using the Duke criteria, which were updated in 2023. In the Duke-ISCVID 2023 criteria, Gemella was recognised as a typical IE pathogen. This study investigates the impact of this change and compares the clinical characteristics of Gemella IE to IE caused by other pathogens.

Methods: Data on IE caused by Gemella species and other pathogens was retrieved from the Swedish Registry of Infective Endocarditis (SRIE). Clinical characteristics of Gemella IE were compared to episodes of IE caused by non-beta haemolytic streptococci, by Staphylococcus aureus and by enterococci.

Results: In the SRIE, 29 episodes of Gemella IE were identified among a total of 7677 registered episodes, corresponding to 0.4% of all cases. The most common species were Gemella morbillorum (47%) and Gemella bergerii (27%). The proportion of episodes meeting the criteria for definite IE increased from 13 (45%) with the modified Duke criteria to 21 (72%) with the Duke-ISCVID criteria. Median age of patients with Gemella IE was 70 years, 40% were females and 90% hade native valve IE. One third of the patients underwent heart valve surgery and only one patient (3%) died. Many clinical aspects of IE caused by Gemella resembled those of IE caused by non-beta haemolytic streptococci.

Conclusions: Gemella IE is a rare condition and shares several characteristics with IE caused by non-beta haemolytic streptococci. The prognosis of IE caused by Gemella appears to be relatively favourable.