Asurgical site infection (SSI) develop whenbacteria infiltrate the body throughsurgical incisions.[1] These bacteria may come from the patient's ownskin, thesurgical instruments, or the environment in which the procedure is performed.[2]
An infection is designated as an SSI if it develops at the site of asurgical wound, either because ofcontamination during surgery or as a result of postoperative complications. For the infection to be classified as an SSI, it should occur within 30 days after surgery or within 90 days if animplant is involved.[3]
Surgical site infections that are limited to the skin andsubcutaneous tissues are classified as superficial incisional SSIs. Theseinfections are the most common type, accounting for more than 50% of all reported surgical site infections.[3]
The symptoms of a surgical site infection (SSI) can vary depending on the severity and type of infection. Common signs includeredness andpain around the area of the surgical wound. A cloudy orpurulent fluid maydrain from the wound, indicating infection.Fever is anothercommon symptom, which may accompany other signs such as increased warmth,swelling, or delayed healing at the surgical site. Additional symptoms may also occur, depending on the nature and extent of the infection.[4]
SSIs occur in different areas such as skin,tissue,organs, "implanted material, like ahip replacement".[4]
TheCenters for Disease Control and Prevention (CDC) classifies SSIs into three categories: superficial incisional, deep incisional, and organ/space infections.
The microorganisms responsible for surgical site infections (SSIs) are often derived from endogenousflora. The specific pathogens involved typically vary depending on the type of surgical procedure performed. Among the most frequently identified organisms arestaphylococcus aureus, coagulase-negativestaphylococci,enterococcus faecalis, andescherichia coli. Thesepathogens reflect themicrobiological environment of the surgical field and the body sites exposed during the operation.[6]
SSIs are a significant cause of complications followingsurgery, contributing to both perioperativemorbidity andmortality. These infections are responsible for a large number of healthcare-associated infections globally, including over 2 million cases annually in the United States alone.[3]
There has been ongoing research on the SSIs, with theNational Institute for Health and Care Research (NIHR) Global Research Health Unit on Global Surgery and GlobalSurg Collaborative. Several keypoints have been identified as Low income countries have a disproportionately greater burden of SSIs (with 4 times the burden in children) than other countries and higher rates of antibiotic resistance.[7][8] More studies have investigated the role of perioperative high fractionOxygen andTelemedicine in preventing and improving outcomes of SSIs.[9][10]
A study conducted by researchers at theUniversity of Washington School of Medicine, published in 2024 and featured by theUniversity of Minnesota[11] and theAmerican Association for the Advancement of Science,[12] andNature[13] involved 210 adult patients undergoingspinal fusion surgery and found that most infections following surgery were caused by bacteria already present on the patients' skin.[14][15]
The researchers aimed to understand why surgical site infections (SSIs), which occur in about 1 in 30 surgeries, have not decreased despiteinfection prevention measures. They analyzed preoperativepatient microbiomes and postoperative SSI samples usinggenomic analysis.[14] Of the 210 patients, 14 (6.8%) developed SSIs. Skin,nasal, andrectal samples were taken before surgery from most patients.Whole genome sequencing of 22 SSI samples revealed that 86% were similar to bacterial strains found on the patients' skin before surgery. Further analysis of 59 additional SSIs in the same hospital showed no common bacterial strains, suggesting that the infections were not linked to external hospital sources.[14]
A recent study of 150 adults undergoing ortho-spine procedures were randomized subjects pre-operatively to self-cleanse at home with 2% chlorhexidine gluconate and aloe-vera infused wipes or soap and water the night prior to surgery. Skin cultures were collected pre-cleansing, day of surgery at admission pre-operative, at hospital discharge and at the post-operative follow up visit with the surgeon (4-6 weeks post operative). The study revealed those cleansing with chlorhexidine gluconate (CHG) had statistically significantly less bacterial skin burden (including pathogens commonly associated with development of surgical site infections) than those who used soap and water. This protection lasted up to 4 days, perhaps due to the inclusion of aloe vera in the wipes moistening the skin allowing the CHG to cross several epidermal layers. This is important as the first 3-4 days after incision is the most vulnerable time as the skin epithelizes and heals forming a barrier to pathogens.[16]
A 2025 study of adults undergoing surgery for extremity or pelvic fractures reported that iodine povacrylex inisopropyl alcohol, when used for preoperative skin antisepsis in closed fracture surgery, was associated with fewer surgical site infections within 90 days thanchlorhexidine gluconate in isopropyl alcohol. Infection rates after open fractures and the likelihood of unplanned fracture-related reoperation within one year were similar between the two antiseptic solutions.[17]
A 'Global Surgical-Site Infection' score was published byNIHR Global Research Health Unit on Global Surgery and GlobalSurg Collaborative that allows the SSIs risk prediction with perioperative variables.[18]