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KEY POINTS
Staphylococcus aureus, the most common pathogen associated with surgical site infections, has numerous virulence factors that facilitate invasion and thwart host defenses.
Bacterial counts in the proximal gastrointestinal tract are in the range of 104 to 105 colony-forming units (CFU)/mL, whereas numbers in the terminal ileum (108–1010 CFU/mL) approach those in the colon (1011–1012 CFU/mL).
When childhood immunizations have not been given and there is a tetanus-prone wound, tetanus toxoid as well as tetanus immune globulin at a separate site should be administered.
Approximately 25% of soft tissue infections from Vibrio vulnificus are caused by direct exposure of an open wound to warm seawater containing the organism.
Class IV wounds are characterized by pus or extensive and prolonged contamination and had a historic infection rate of 30% if closed primarily.
When using alcohol-based skin disinfectants in the operating room, it is imperative that the solution be dry prior to incision to lower the risk of an intraoperative fire.
Acute infections in soft tissue still present with calor (heat), dolor (pain), rubor (redness), tumor (swelling), and loss of function (functio laesa).
Intra-abdominal infections identified later in the hospital course (>4 days after injury) are more likely to be caused by hospital-associated rather than community-associated organisms.
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Death after traumatic injury has been described in terms of a bimodal distribution. Immediate and acute (<24 hours) deaths usually result from uncontrolled hemorrhage, but infections and multiple organ dysfunction syndrome, which often arise from infection, are responsible for a significant proportion of late deaths. Indeed, infection is responsible for most deaths in patients who survive longer than 48 hours after trauma.1 Trauma-related infections can be divided into those that result directly from the injury (eg, due to contamination that occurs in conjunction with the traumatic injury) and nosocomial infections that arise in the health care setting in conjunction with treatment of the injury. The pathogens involved can be exogenous or endogenous bacteria, depending on the mechanism of injury and/or the iatrogenic cause.
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Most posttraumatic infections are polymicrobial, involving a mixture of aerobic and anaerobic organisms.2 In one series, 37% to 45% of all trauma patients experienced infectious complications during their initial hospitalization.3 In that same study, 80% of trauma patients who were in the intensive care unit (ICU) at least 7 days met the criteria for the systemic inflammatory response syndrome (SIRS). All caregivers need to understand the principles of surgical infections in the context of traumatic injury. This chapter will review the following: factors that normally prevent infection, how trauma disrupts or overwhelms normal host defenses, recognition and treatment of the most common infectious complications after traumatic injury, principles of infection prevention, and how prophylaxis and prevention principles can be applied chronologically during the treatment of trauma patients.
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PATHOGENESIS OF INFECTION
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