Virulence of beta-hemolytic streptococci in infective endocarditis



Streptococci involved in infective endocarditis (IE) primarily comprise alpha- or non-hemolytic streptococci (ANHS). Moreover, beta-hemolytic streptococci (BHS) can be involved, and guidelines recommend the addition of gentamicin for the first 2 weeks of treatment and the consideration of early surgery in such cases. This study compared the morbidity and mortality associated with IE depending on the microorganisms involved (BHS, ANHS, staphylococci, and enterococci).


We conducted a retrospective observational study between 2012 and 2017 in a single hospital in France. The endpoints were overall in-hospital mortality, 1-year mortality and the occurrence of complications.


We analyzed 316 episodes of definite IE including 150 (38%), 96 (25%), 46 (12%), and 24 cases (6%) of staphylococcal, ANHS, enterococcal, and BHS IE, respectively. In-hospital mortality was significantly higher in the staphylococcal (n = 40; 26.7%) and BHS groups (n = 6; 25.0%) than in the ANHS (n = 9; 9.4%) and enterococcal groups (n = 5; 10.9%) (all p < 0.01). The rates of septic shock and cerebral emboli were also higher in the BHS group than in the ANHS group [n = 7 (29.2%) vs. n = 3 (3.1%), p < 0.001; n = 7 (29.2%) vs. n = 12 (12.5%); p = 0.05, respectively].


This study confirmed that BHS IE has a more severe prognosis than ANHS IE. The virulence of BHS may be similar to that of staphylococci, justifying increased monitoring of these patients and more ‘aggressive’ treatments such as early surgery.

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We thank François Lefebvre for his help in the statistical analysis. The authors would like to thank Enago ( for the English language review.


This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

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YR, XA, and YH designed the study. YR, XA, YH, AM, NL, ND, and JPM collected the data. YR and XA analyzed the data. PR analyzed the microbiological data. YR performed the statistical analysis. YR and XA wrote the manuscript. All authors reviewed, revised, and approved the final report.

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Correspondence to Yvon Ruch.

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Ruch, Y., Hansmann, Y., Riegel, P. et al. Virulence of beta-hemolytic streptococci in infective endocarditis. Infection 48, 91–97 (2020).

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  • Infective endocarditis
  • Streptococci
  • Beta-hemolytic
  • Virulence
  • Cardiac surgery