Exploration of Shoulder Abscess Association With Prompt Aggregatibacter aphrophilus Growth in Infective Endocarditis

Aggregatibacter aphrophilus, formerly known as Haemophilus aphrophilus, is one member of a group of bacteria referred to as HACEK (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella) organisms. Infections from any of the HACEK organisms typically lead to very poor outcomes and can be difficult to manage, especially when complicated by intracranial hemorrhage (ICH). HACEK organisms can also be difficult to grow on blood cultures, and A. aphrophilus is rarely seen, if at all. Traditionally, most laboratories follow an extended incubation protocol of 14 to 21 days to aid the growth of HACEK bacteria. Herein we report a case of infective endocarditis where A. aphrophilus resulted on blood culture in three days, in a patient with a right shoulder abscess, complicated by septic embolization leading to ICH. We explore a potential link between the prompt growth of A. aphrophilus on blood culture and the presence of the right shoulder abscess.