The aim of this study is to systematically explore the perioperative presence of P acnes in all layers of sternal wound incision as well as contamination of graft material and prosthetic valves during primary operation. Secondly, to compare if different regimes of antibiotics affects the bacterial growth.

Cultures will be taken from the skin, subcutaneous, and from the implanted valve prostheses with a rayon swab.Graft and Felt material will, after being pressed subcutaneous for 15 sec, placed into prepared sterile bottles containing broth for aerobe and anaerobe cultures. Surgical gloves will be cultured.

Inclusion Criteria:

• Open cardiac surgery; coronary artery bypass grafting, valve replacement/repair or a combination of these.

Exclusion Criteria:

• Skin conditions such as eczema, psoriasis.
• Revision surgery
• Aortic surgery

Consecutive patients undergoing cardiac surgery at the Cardiothoracic and Vascular surgery Department at the University Hospital in Örebro.