Medicine Bacteria responsible for post-operative endocarditis is: A Streptococcus viridans. B Staphylococcus epidermidis. C Streptococcus aureus. D Streptococcus pneumoniae. 💡 Explanation Bacteria responsible for post-operative endocarditis is: ✓ Correct Answer: B. Staphylococcus epidermidis.