Endocarditis caused by nutritionally variant streptococci: a case report and literature review.

Infective endocarditis (IE) due to Abiotrophia and Granulicatella species, previously referred to as nutritionally variant streptococci (NVS), occurs rarely and is often associated with negative blood cultures. Rates of treatment failure, infection relapse and mortality are higher than those of endocarditis caused by other viridans streptococci. We report a case of endocarditis caused by Granulicatella adiacens in a young man with no risk factors, who was successfully treated with surgery and combination antimicrobial chemotherapy, and provide a literature review of endocarditis attributable to these rare species of fastidious gram-positive cocci which have proven exceedingly difficult to treat, with high rates of relapse and therapeutic failure despite in vitro effective antibiotic treatment regimens. Analysis of literature revealed a high prevalence (61%) of valvular heart predisposing conditions associated with endocarditis caused by NVS, such as congenital valvular heart disease or heart valve prosthesis. On the other hand, 39% of cases showed no evidence of risk factors. Combination antimicrobial chemotherapy with penicillin and gentamicin represents the antimicrobial treatment of choice in the management of patients with IE attributable to NVS. Heart valve replacement surgery should be considered in cases of hemodynamic derangement due to significant valve destruction.