Surgical Site Infections

Primitive ancestors of Homo sapiens and their colonizing bacteria have coevolved for approximately 500,000 years; some experts estimate that the total number of human cells is 1013 and the total number of colonizing microbes is 1014. Despite this 10-to-1 inequity, the balance of power is influenced by an intact human immune system and the integrity of the skin and mucous membranes. Operative procedures disrupt this balance, resulting in a risk of surgical-site infections from endogenous flora, including colonizing strains of Staphylococcus aureus.

The Centers for Disease Control and Prevention (CDC) term for infections associated with surgical procedures was changed from surgical wound infection to surgical site infection in 1992 . These infections are classified into incisional, organ, or other organs and spaces manipulated during an operation; incisional infections are further divided into superficial (skin and subcutaneous tissue) and deep (deep soft tissue-muscle and fascia). These definitions should be followed universally for surveillance, prevention, and control of surgical site infections.

Surgical site infections (SSIs) initiated during invasive procedures can require additional and/or extended treatment. Despite the best efforts of healthcare facilities to maintain safe surgical environments, surgical site infections result in up to $10 billion in treatment costs every year in the U.S. alone.
* 780,000 out of 30 million surgical procedures performed annually in the U.S. result in SSI.1
* In the United Kingdom, the estimated direct costs for a patient who has developed a surgical site infection are between €2,265 and €2,518.2
* According to a study in the Netherlands, SSIs result in 5.8 to 17 extra days of hospitalization.3
* In France, approximately 11% of surgical patients acquire a surgical site infection.4

Some common causes of SSI are:
* Complications from surgical hypothermia
* Contamination of the incision area by skin flora
* Bacterial cross–contamination
* Surgical instrument contamination

The pathogens isolated from infections differ, primarily depending on the type of surgical procedure. In clean surgical procedures, in which the gastrointestinal, gynecologic, and respiratory tracts have not been entered, Staphylococcus aureus from the exogenous environment or the patient's skin flora is the usual cause of infection. In other categories of surgical procedures, including clean-contaminated, contaminated, and dirty, the polymicrobial aerobic and anaerobic flora closely resembling the normal endogenous microflora of the surgically resected organ are the most frequently isolated pathogens

The most critical factors in the prevention of postoperative infections, although difficult to quantify, are the sound judgment and proper technique of the surgeon and surgical team, as well as the general health and disease state of the patient. Other factors influence the development of postoperative wound infection, especially in clean surgical procedures, for which the infection rate (<3%) is generally low. Infections in these patients may be due solely to airborne exogenous microorganisms

Article taken from:
http://www.cdc.gov/ncidod/eid/vol7no2/nichols.htm
http://www.nejm.org/doi/full/10.1056/NEJMe0908753
http://www.haiwatch.com/SSI.aspx?Region=UK