Level 1	Preoperative transfusion may increase the risk of surgical-site infection (SSI)
	Laparoscopic operations lead to a lower incidence of SSI than open operations because the total length of the incisions is shorter, reducing the risk of bacteria entering the subcutaneous space
Level 2	In elderly patients, chronic obstructive pulmonary disease (COPD) and low preoperative serum albumin are independent predictors of wound infections; coronary artery disease (CAD), COPD, low preoperative serum albumin, and steroid use are independent predictors of a longer hospital stay
	Patients who undergo ventral hernia repair with a simultaneous bowel resection show a higher incidence of infectious and noninfectious complications with mesh use
	Wound infection is lower in laparoscopic hernia repair than in open repair due to the decreased extent of tissue dissection
	Mesh, wherever possible, should not be brought in contact with skin to avoid contamination by skin flora. Polyester meshes are associated with the highest incidence of infection, fistualization, and recurrence
	Patients given a prophylactic antibiotic have a lower incidence of SSI
Level 3	Patient operation time is the only significant risk factor associated with infection of mesh graft after incisional hernia repair
	Patient age, American Society of Anesthesiology (ASA) score, smoking, surgery duration, and an emergency setting of the operation are associated with the development of synthetic mesh infection
	Complications are significantly associated with larger hernias, previous herniorrhaphy, longer operating times, and extended hospital stays
Level 4	Patient characteristics that increase the risk of SSI include steroid use, smoking, old age, and underlying disorders such as obesity, diabetes, malnutrition, and remote-site infection
	The source of SSI is skin flora or bacterial contamination from a viscus
	The use of the mesh does not increase the incidence of SSI, although the consequences of the mesh infection may be severe
	If the mesh is placed subcutaneously, SSI is more common than if it is placed in a subaponeurotic premuscular, pre-aponeurotic retromuscular, or preperitoneal space. If infection is present, repair by tension-free nonabsorbable prosthetic implants is not recommended
	A prolonged preoperative hospital stay and preoperative nares colonization with Staphylococcus aureus increase the risk of SSI
	The presence of drainage and its duration increases the incidence of SSI. If an indication for drainage exists, it should be as short as possible