Yes, the prescribed antibiotic, sultamicillin, is generally safe and appropriate for post-CABG patients to treat bacterial infections, provided you have no penicillin allergies. However, any fluid or pus leaking from a chest incision after heart surgery requires immediate attention to ensure proper healing. Your next steps are: 1. Start the medication exactly as prescribed. 2. Keep the wound clean and dry; do not apply unprescribed ointments. 3. Contact your cardiac surgical team immediately to have the wound physically evaluated. This is a standard precautionary step to monitor your recovery and prevent deeper infection. Rest assured, with prompt medical evaluation and the right antibiotics, this can be managed effectively.