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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
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        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).
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