Infective endocarditis caused by Streptococcus acidominimus

Am J Health Syst Pharm. 2019 Nov 13;76(23):1926-1929. doi: 10.1093/ajhp/zxz234.


Purpose: A case of infective endocarditis caused by Streptococcus acidominimus is reported.

Summary: An 81-year-old Caucasian man underwent an elective transcatheter aortic valve implantation due to his severe aortic valve stenosis. He presented to the hospital 3 weeks later with a 1-week history of fever (39ºC) that did not resolve following a 3-day course of azithromycin and a 5-day course of ciprofloxacin. Three sets of blood sample cultures were taken. Empirical antimicrobial treatment was initiated to target gram-positive and gram-negative microorganisms and consisted of vancomycin 1 g intravenous (i.v.) every 12 hours and imipenem-cilastatin 500 mg i.v. every 6 hours. After 48 hours, the blood culture was positive for S. acidominimus. The strain was sensitive to ampicillin, cephalosporins, tetracycline, and vancomycin. It was resistant to penicillin, macrolides, trimethoprim-sulfamethoxazole, and fosfomycin. Transesophageal echocardiography showed a small mobile vegetation attached to the anterior mitral valve leaflet, along with mild mitral regurgitation. The patient was diagnosed with native mitral valve infective endocarditis, and imipenem-cilastatin was discontinued. The patient showed clinical and laboratory improvement during his 2-week hospitalization. A peripherally inserted central catheter was put in place, and the patient was discharged on i.v. vancomycin to complete a total of 6 weeks treatment, after which the infection resolved.

Conclusion: An 81-year-old man diagnosed with mitral valve endocarditis caused by S. acidominimus was successfully treated with vancomycin.

Keywords: Streptococcus acidominimus; endocarditis; vancomycin.

Publication types

  • Case Reports

MeSH terms

  • Aged, 80 and over
  • Aortic Valve Stenosis / surgery
  • Endocarditis, Bacterial / diagnosis
  • Endocarditis, Bacterial / drug therapy
  • Endocarditis, Bacterial / microbiology*
  • Humans
  • Male
  • Postoperative Complications / diagnosis
  • Postoperative Complications / drug therapy
  • Postoperative Complications / microbiology*
  • Streptococcal Infections / diagnosis
  • Streptococcal Infections / drug therapy
  • Streptococcal Infections / microbiology*
  • Streptococcus / isolation & purification*
  • Streptococcus / pathogenicity
  • Transcatheter Aortic Valve Replacement / adverse effects
  • Treatment Outcome
  • Vancomycin / therapeutic use*


  • Vancomycin

Supplementary concepts

  • Streptococcus acidominimus