Cardiobacterium Valvarum Bacteremia in a Left Ventricular Assist Device Recipient: Case Report and Review of the Literature

Abstract

Introduction Cardiobacterium valvarum is a HACEK organism known for causing infective endocarditis (IE); there are no reported cases implicating this bacterium in left ventricular assist device (LVAD) infections in the English literature. Case Report A 59 year old gentleman with sarcoidosis, systolic heart failure (EF 15%), BiV-ICD (implanted 11/2015) and LVAD (Heartware implanted 10/2017) presented with fever and cough. He experienced worsening lower extremity edema and abdominal girth one week prior to admission. In the emergency room his temperature was 39.5°C and had mild erythema without drainage at his drive line exit site (DLES). Labs were notable for WBC of 15.5 × 103/μL and lactic acid of 2.2 mmol/L. Blood cultures were obtained and the patient received piperacillin-tazobactam and vancomycin. TTE and CT imaging of chest and abdomen demonstrated no significant findings. The initial blood culture became positive with gram-negative bacilli after 3.5 days and were identified as C. valvarum 28 days after initial presentation. He completed a two-week course of ertapenem and transitioned to cephalexin 500 mg BID as secondary prophylaxis. Erythema at the DLES improved and heart failure symptoms resolved. The patient remained on this regimen until transplant, 348 days from positive culture. The organisms classified in the HACEK (Haemophilus spp., Aggregatibacter spp., Cardiobacterium spp., Eikenella spp., and Kingella spp.) group are known for being fastidious causes of IE; they are not traditionally associated with pump, line, or pocket infections in VAD patients. The most common gram-negative bacterial infections associated with VADs and their components are P. aeruginosa and enteric organisms. This patient's case was treated as a VAD-related blood stream infection. Because Cardiobacterium spp. are oral commensals, DLES as the source was less likely. As noted in the IE guidelines, the presence of a HACEK organism without an identifiable source should be considered IE unless proven otherwise, even if there are no other stigmata of IE. Thus, despite only one culture growing C. valvarum, there was a high suspicion for the components of the VAD being seeded, resulting in antibiotic suppression until transplantation. Summary In the presence of a VAD, HACEK organism found in the bloodstream should be treated as a pump infection unless proven otherwise.