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CHAPTER 16

Surgical Site Infection

Abdulrasheed A. Nasir
Sharon Cox
Emmanuel A. Ameh

Introduction an increasing risk of SSIs were described: clean, clean-contaminated,
Infection is the clinical manifestation of the inflammatory reaction contaminated, and dirty (Table 16.1). The simplicity of this system of
incited by invasion and proliferation of microorganisms. Despite classification has resulted in its widespread use to predict the rate of
1
modern surgical techniques and the use of antibiotic prophylaxis, infection after surgery.
surgical site infection (SSI) is one of the most common complica- The term used by the Centers for Disease Control and Prevention
tions encountered in surgery. SSI places a significant burden on both (CDC) for infections associated with surgical procedures was changed
the patient and health system, especially in Africa where resources from surgical wound infection to surgical site infection by the Surgical
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are limited. SSI occurs in up to 40% of surgical procedures, delaying Wound Infection Task Force in 1992. Infections are classified
recovery by one week on average and often resulting in the need for by the depth of the tissue involved: superficial incisional (skin
further surgical procedures. It is still a major limiting factor in advanc- and subcutaneous tissue), deep incisional (deep soft tissue–muscle
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ing the horizons of surgery in spite of the progress made in its control. and fascia), and organ space (any part of the anatomy opened or
SSI is thus a major cause of morbidity, prolonged hospital stay, and manipulated during the procedure other than the incision).
increased health costs. 4 Superficial Incisional SSI
Demographics A superficial incisional infection occurs within 30 days after the opera-
tion. It involves only the skin or subcutaneous tissue of the incision. At
Although a large number of reports on SSI are available in adult lit-
5–8

erature, reports for children are few, and most are from developed least one of the following is present:
countries with an overall incidence of 2.5–20%. 4,9–13 In most of Africa, • purulent drainage, with or without laboratory confirmation, from
incidence data are not available, but one hospital-based prospective the superficial incision;
report suggests an incidence of 23.6%. 14 • organisms isolated from an aseptically obtained culture of fluid or
Classification tissue from the superficial incision;
SSIs are defined as infections occurring within 30 days of the pro- • at least one of the following signs or symptoms of infection: pain
cedure and involving the operative area. Where implants have been or tenderness, localised swelling, redness, or heat and superficial
placed, this time period is extended to 1 year if the infection appears incisions deliberately opened by the surgeon, unless the incision is
to relate to the procedure. 3 culture-negative; or
A system of classification for operative wounds that is based on the • diagnosis of superficial incisional SSI by the surgeon or attending
degree of microbial contamination was developed by the US National physician.
Research Council (NRC) group in 1964. Four wound classes with
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Deep Incisional SSI
A deep incisional SSI occurs within 30 days after the operation if no
Table 16.1: Classification of operative wounds based on degree of implant is left in place, or within 1 year if an implant is present. It
microbial contamination.
involves the deep soft tissues (e.g., fascial and muscle layers) of the
Classification Criteria incision. At least one of the following is present:
Clean Elective, nonemergency, nontraumatic case, primarily • purulent drainage from the deep incision but not from the organ
closed; no acute inflammation; no break in aseptic space component of the surgical site;
technique; respiratory, gastrointestinal, biliary, and
genitourinary tracts not entered. • a deep incision spontaneously dehisces or is deliberately opened by
Clean-contaminated Urgent or emergency case that is otherwise clean; a surgeon when the patient has at least one of the following signs or
elective opening of respiratory, gastrointestinal, biliary, symptoms: fever (>38°C), localised pain, or tenderness, unless the
or genitourinary tract with minimal spillage (e.g., site is culture-negative;
appendectomy) not encountering infected urine or bile;
minor aseptic technique break. • an abscess or other evidence of infection involving the deep inci-
Contaminated Nonpurulent inflammation; gross spillage from sion is found on direct examination, during reoperation, or by his-
gastrointestinal tract; entry into biliary or genitourinary topathologic or radiologic examination; or
tract in the presence of infected bile or urine; major
break in aseptic technique; penetrating trauma <4 hours • diagnosis of a deep incisional SSI by the surgeon or attending physician.
old; chronic open wounds to be grafted or covered.
Organ Space SSI
Dirty Purulent inflammation (e.g., abscess); preoperative
perforation of respiratory, gastrointestinal, biliary, or An organ space SSI occurs within 30 days after the operation if no
genitourinary tract; penetrating trauma >4 hours old. implant is left in place, or within 1 year if an implant is present. It
involves any part of the anatomy (e.g., organs or spaces), other than
Source: B’ernard F, Grandon J, Postoperative wound infections: the influence of ultraviolet
irradiation of the operating room and of various other factors. Ann Surg 1964; 160(Supp 1).