title: Infective endocarditis due to penicillin-resistant viridans group streptococci.
abstract: BACKGROUND
  The emergence of viridans group streptococci that are relatively or fully resistant to penicillin is increasingly being recognized worldwide, but only a scant number of penicillin-resistant isolates have been described as a cause of infective endocarditis. Because of the paucity of data, it has been difficult to define optimal treatment regimens for this syndrome. Thus, recommendations for therapy have largely been made on the basis of consensus opinion.
  
  
  METHODS
  We retrospectively identified a cohort of patients with infective endocarditis due to penicillin-resistant viridans group streptococci who were seen at the Mayo Clinic (Rochester, MN) between January 1967 and April 2006. Demographic characteristics, clinical features, treatment regimens, and outcomes were analyzed. Mean values are shown with standard deviations.
  
  
  RESULTS
  Twenty-nine patients were identified over the 38.5-year study period. Nineteen patients with native valve endocarditis were cured; 9 of these 19 patients received a 2.3+/-0.4-week antibiotic regimen consisting of penicillin and an aminoglycoside, and 8 of these 19 patients received treatment courses of 5.1+/-1.4 weeks' duration that consisted of either a bimodal combination regimen with a penicillin or ceftriaxone and an aminoglycoside or ceftriaxone monotherapy. Nine of 10 patients with prosthetic valve infection were cured with 4.1+/-0.6-week regimens that consisted of either a combination regimen or monotherapy with vancomycin or ceftriaxone. Mean duration of follow-up after hospital discharge was 9.1 years.
  
  
  CONCLUSIONS
  Outcomes of this relatively large population of patients with endocarditis with a prolonged duration of follow-up indicate that the application of current treatment guidelines should be successful in most patients.
authors.affiliation: Department of Medicine, Mayo Clinic College of Medicine, Rochester, MN 55905, USA. Knoll.Bettina@mayo.edu
authors.forename: Bettina
authors.initials: B
authors.lastname: Knoll
authors.forename: Imad M
authors.initials: IM
authors.lastname: Tleyjeh
authors.forename: James M
authors.initials: JM
authors.lastname: Steckelberg
authors.forename: Walter R
authors.initials: WR
authors.lastname: Wilson
authors.forename: Larry M
authors.initials: LM
authors.lastname: Baddour
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D017714:Community-Acquired Infections; D003428:Cross Infection; D018572:Disease-Free Survival; D004697:Endocarditis, Bacterial / Q000188:drug therapy* / Q000382:microbiology; D005260:Female; D006350:Heart Valve Prosthesis / Q000382:microbiology*; D006784:Hospitals, Teaching; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010403:Penicillin Resistance / Q000187:drug effects; D017410:Practice Guidelines as Topic; D012189:Retrospective Studies; D013290:Streptococcal Infections / Q000188:drug therapy*; D016896:Treatment Outcome; D034363:Viridans Streptococci / Q000187:drug effects* / Q000472:pathogenicity