Abiotrophia defectiva bacterial endocarditis complicated by an infective intracranial mycotic aneurysm - The need for...

Abiotrophia defectiva or nutritionally variant streptococci (NVS) was first described in 1961 as a rare cause of infectious endocarditis (IE). It is distinct to the Streptococcus genus, pleomorphic, and demonstrates variable Gram-staining characteristics due to poor growth in culture media requiring extended incubation or 16S rRNA sequencing in culture negative situations.¹ NVS has also been implicated in the pathogenesis of culture-negative endocarditis. In comparison with other causes of endocarditis, it has the ability to secrete exopolysaccharide and adheres to fibronectin in the extracellular matrix of endovascular structures.² NVS is associated with significant morbidity and mortality, higher rates of multisystem complications ranging from pancreatic abscess, intracranial aneurysms, osteomyelitis, and valvular destruction, despite sensitivity to antibiotics.