Surgical site infections (SSIs) are infections that occur after surgery in the part of the body where the surgery took place. These infections can be superficial, involving the skin only, or more serious, affecting tissues under the skin, organs, or implanted material. SSIs are among the most common healthcare-associated infections (HAIs), posing significant risks to patient recovery. They can vary in severity from mild, localized infections to severe, life-threatening conditions. The risk of developing an SSI depends on several factors, including the type of surgery, the surgical environment, the patient's health condition, and the adequacy of infection control practices. Prevention of SSIs is crucial and involves various strategies such as appropriate surgical scrubbing, the use of sterile techniques during surgery, administering prophylactic antibiotics when indicated, and ensuring good postoperative care. Monitoring for signs of infection is essential for early detection and treatment to prevent complications. 

The number of surgical site infections (SSIs) occurring annually can vary widely depending on the country, the types of surgeries performed, and the healthcare practices in place. In the United States, for example, the Centers for Disease Control and Prevention (CDC) estimates that SSIs occur in 2-5% of patients undergoing inpatient surgery. This translates to about 157,500 SSIs annually based on the data available for surgeries performed in hospitals. Globally, the incidence can be higher, especially in regions with less developed healthcare infrastructures. SSIs remain a significant challenge due to their impact on patient outcomes, including prolonged hospital stays, increased healthcare costs, and higher rates of morbidity and mortality. Efforts to reduce the rate of SSIs focus on improving surgical techniques, sterilization methods, and postoperative care.