Sternal Wound Infections

Abstract

Sternal wound infections are common complications following open heart surgery despite advanced prevention strategies. Fortunately, most of these are superficial infections that respond to antibiotics and wound debridement. In 0.25–5% of cases, however, they extend below the sternum into the anterior mediastinum, often called deep sternal wound infections (DSWIs) or postoperative mediastinitis that can be fatal. Most DSWIs are detected early within the first month following surgery but late chronic infections with sternocutaneous fistulas can also be encountered. The most common pathogens in DSWI are coagulase-negative staphylococci (CoNS), followed by Staphylococcus aureus and Gram-negative bacteria. These infections are usually detected after purulent discharge from the wound, fever, or following sternal dehiscence or mediastinal widening on chest X-ray with or without sepsis and culture of organisms from blood or mediastinal tissue and fluid. Numerous risk factors have been identified with diabetes mellitus, obesity, peripheral arterial disease, chronic renal failure and smoking with chronic pulmonary disease being the most important ones. Treatment consists of intravenous antibiotics, commonly vancomycin until results from antimicrobial susceptibility tests are available. For DSWI surgical treatment usually starts with debridement of the wound with several surgical approaches available for definitive treatment. In recent years negative-pressure wound therapy (NPWT) has gained popularity as it can stabilize the sternum and promote granulation of the wound from below. At the same time it is less laborious compared to conventional wound dressing changes or closed suction irrigation. Morbidity and both short- and long-term mortality are negatively associated with DSWI, but with advances in treatment mortality has dropped significantly and in recent reports ranges between 1% and 14%. This chapter provides an overview of the clinical presentation, pathogenesis, microbiology, preventive measures and management of sternal wound infections following open heart surgery.