title: Aortic Valve Endocarditis Caused by Abiotrophia defectiva: Case Report and Literature Overview.
abstract: Abiotrophia defectiva or nutritionally variant Streptococcus (NVS) are a rare but important cause of infectious endocarditis, with high rates of bacteriological failure and mortality. We report the case of a 74-year-old man admitted for fever, fatigue and general malaise in the absence of any underlying cardiac, immunosuppressive illness and previous dental manipulations. Transthoracic and transesophageal echocardiogram revealed bacterial vegetation and significant aortic stenosis and regurgitation. Initial blood culture reported gram-positive cocci in chains, subsequently identified as A. defectiva. The patient completed 6 weeks of antibiotic therapy with ampicillin, with a significant decrease of serum inflammatory markers. He refused cardiac surgery and had relapsing endocarditis with positive blood culture for the same pathogen. The patient was then submitted to double-valve cardiac surgery, obtaining a prompt resolution of clinical signs and symptoms, without other relapse or any complications.
  
  
  CONCLUSIONS
  Infectious diseases caused by A. defectiva are extremely rare illnesses. Due to the difficult isolation of the pathogen and the slow clinical progression, clinicians should be aware of this bacterium when dealing with blood culture-negative infective endocarditis.
authors.affiliation: Third Unit of Infectious Diseases, D. Cotugno Hospital, A.O. Dei Colli, Naples, Italy.
authors.forename: Maria Aurora
authors.initials: MA
authors.lastname: Carleo
authors.affiliation: Microbiology Unit, V. Monaldi Hospital, A.O. Dei Colli, Naples, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Del Giudice
authors.affiliation: Third Unit of Infectious Diseases, D. Cotugno Hospital, A.O. Dei Colli, Naples, Italy.
authors.forename: Rosaria
authors.initials: R
authors.lastname: Viglietti
authors.affiliation: Fifth Unit of Infectious Diseases, D. Cotugno Hospital, A.O. Dei Colli, Naples, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Rosario
authors.affiliation: Fifth Unit of Infectious Diseases, D. Cotugno Hospital, A.O. Dei Colli, Naples, Italy esposvin@libero.it.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Esposito
mesh_terms: D058835:Abiotrophia / Q000145:classification / Q000187:drug effects / Q000235:genetics; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D001021:Aortic Valve / Q000382:microbiology* / Q000601:surgery; D004697:Endocarditis, Bacterial / Q000175:diagnosis / Q000188:drug therapy / Q000382:microbiology* / Q000601:surgery; D016908:Gram-Positive Bacterial Infections / Q000175:diagnosis / Q000188:drug therapy / Q000382:microbiology*; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents
keywords: Abiotrophia defectiva; NVS; blood culture; infectious endocarditis; nutrionally variant streptococci; valve