A 51-year-old man with no prior history presented with a 2-day complaint of right leg pain and swelling. He was undergoing an outpatient work up for a 6-month history of chronic cough and 60 lb weight loss. He endorsed subjective fevers and fatigue that kept him in bed for 12 hours a day. Vital signs were notable for a temperature of 101.0°F, HR 98 beats/min, BP 101/51 mmHg, respiratory rate of 18 breaths/min and oxygen saturation of 100% on room air. Exam was significant for swelling and erythema of the right lower extremity. Heart and lung sounds were normal with no murmur auscultated. Laboratory studies were significant for WBC count of 13.6 (80% neutrophils), d-dimer 2.5, CRP 8.3, and ESR of 52. Lower extremity ultrasound was positive for thrombus in the right posterior tibial vein. A CT PE protocol was negative except for moderate hilar lymphadenopathy. An transthoracic echocardiogram (TTE) showed EF 60-65%, LA moderately enlarged, moderate aortic regurgitation, and mild mitral regurgitation. Blood cultures drawn on admission resulted in gram variable rods on day 3 of admission and repeat blood cultures were drawn on hospital day 3. Due to patient preference, he was discharged with warfarin and enoxaparin for his DVT on day 6 of admission. Repeat blood cultures grew gram variable rods three days following discharge. Ten days after discharge his blood culture resulted as Cardiobacterium Hominis (C hominis). He was contacted and re-admitted to the hospital for further work up. A repeat TTE showed EF 40-45%, severe aortic regurgitation, and 5×6 mm mass on the aortic valve. He subsequently had a transesophageal echocardiogram that confirmed the diagnosis of aortic valve endocarditis with vegetation. He was referred to cardiology and cardiothoracic surgery for aortic valve replacement.
Positive blood cultures are frequently encountered in the inpatient setting. Slow-growing blood cultures are often considered due to a contaminated specimen. However, these blood cultures should be followed for final identification. Cardiobacterium hominis is an example of a slow-growing fastidious organism. With persistently positive blood cultures, hospitalists become concerned about endocarditis.
C hominis is an uncommon cause of endocarditis. It is a member of the HACEK group of microorganisms (Haemophilus species, Actinobacillus actinomycetemcomitans, C hominis, Eikenella corrodens and Kingella kingae). To date, there have been a total of 68 case reports in the English language of C hominis endocarditis. Most of the case presentations represent an indolent course of infection with the average time from onset of symptoms to diagnosis around 145 days. Dental work is thought to be the etiology in 40% of prior case reports. The most common symptoms of subacute endocarditis include weight loss, fatigue, and symptoms associated with heart failure (orthopnea, dyspnea on exertion). The slow growing nature of the HACEK organisms makes diagnosis difficult due to the need to keep blood cultures for 2-3 weeks. Unique to C hominis is an association with distal embolic events. In our case, the presenting complaint of DVT was likely a result of the patient spending long periods of time in bed and the increased systemic inflammation caused by the patient’s endocarditis.
A patient presenting with long-standing systemic symptoms, increased inflammatory makers, and abnormal echocardiogram should prompt the clinician to consider subacute endocarditis on the differential diagnosis.