Infective endocarditis caused by Arcanobacterium haemolyticum: a case report

Arcanobacterium haemolyticum is a facultative anaerobic gram-positive bacillus. Originally classified in the Cornyebacterium genus, it was re-classified in a new genus in 1982 [1]. It has been isolated from the skin and pharynx of healthy individuals and it is a well-recognised cause of pharyngitis, skin and soft-tissue infections [2]. Less commonly, the organism causes deep-seated infections including osteomyelitis [3], brain abscesses [4] and endocarditis [5-7].Arcanobacterium means 'mysterious bacterium', which is an epithet quite befitting for an organism that is frequently overlooked by the Clinical Microbiology laboratory because it is deemed to be a contaminant or normal flora [8]. Recognition of the ability of this organism to cause disease is important in order to make a correct diagnosis and commence appropriate antibiotic therapy.Here we describe the first case of successfully treated A. haemolyticum infective endocarditis complicated with cerebral emboli and review the features of this rarely pathogenic organism.A 21-year-old Caucasian female with known congenital heart disease presented with a five-day history of fever, lethargy and a swollen, painful left calf. Her past medical history included previous surgical repair for pulmonary atresia, quadricuspid aortic valve and a ventricular septal defect (VSD) as a child for which she took life-long warfarin anticoagulation therapy. She had also suffered recurrent miscarriages.On examination she was febrile at 38.5°C, but hemodynamically stable. Significant positive findings were a swollen, tender left lower limb and an ejection flow murmur across the prosthetic aortic valve and pulmonary regurgitation through the pulmonary conduit, consistent with her heart condition. The remainder of the clinical examination was unremarkable.Laboratory results showed: hemoglobin 9.3 g/dl; mean cell volume 0.32 fl; white cell count 8.6 × 109/liter; neutrophil count 6.7 × 109/liter; platelet count 268 × 109/liter; C-reactive