surgical infection

Surgical Infections

Dr.Mahamed Hussein General Surgery Azadi Teaching Hospital

Surgical Infections Introduction

Surgical infections may arise in the surgical wound itself or in other systems in the patient.They can be initiated not only by “damage” to the host but also by changes in the host’s physiologic state.

Surgical InfectionsTwo main types

Community-Acquired Are active process that were initiated before the patient presented for treatment Hospital-Acquired All infections that occur after surgical procedures

Community-Acquired

Skin/soft tissue Cellulitis: Group A strep Abcess/furuncle: Staph aureus Necrotizing: Mixed Hiradenitis suppurativa: Staph aureus Lymphangitis: Staph aureus Gangrene : synergistic
Tetanus Hand infections Foot infections Biliary tract infections Peritonitis Viral infections

Hospital-Acquired

SSI (Wound infection) Pulmonary Urinary Tract Intra-abdominal Empyema Foreign-body associated Fungal infection Multiple organ failure

What is a Surgical Site Infection?

SSI’s can be defined as an infection that is present up to 30 days after a surgical procedure if no implants are placed, and up to one year if an implantable device was placed in the patientThe majority of SSIs will occur during the first 2-3 weeks after surgery


Some definitions
Colonization: presence of bacteria in a wound with no signs or symptoms of systemic inflammation . usually bacterial count less than 10*5cfu/ml Contamination: Transient exposure of a wound to bacteria. Varying concentration of bacteria possible. Time of exposure less than 6 hours. SSI prophylaxis is best strategy. Infection: systemic and local signs of inflammation, bacterial count more than 10*5cfu/ml

Types of Surgical Site Infections

According to the tissue involved: Superficial Deep incisional Organ/space

A superficial incisional SSI must meet one of the following criteria:

Infection occurs within 30 days after the operative procedure and involves only skin and subcutaneous tissue of the incision and patient has at least one of the following: a. purulent drainage from the superficial incision. b. organisms isolated from an aseptically obtained culture of fluid or tissue from the superficial incision. c. at least one of the following signs or symptoms of infection: pain or tenderness, localized swelling, redness, or heat, and superficial incision are deliberately opened by surgeon, and are culture-positive or not cultured. A culture-negative finding does not meet this criterion. d. diagnosis of superficial incisional SSI by the surgeon or attending physician.

A deep incisional SSI must meet one of the following criteria:

An organ/space SSI must meet one of the following criteria:
Infection occurs within 30 days after the operative procedure if no implant is left in place or within one year if implant is in place and the infection appears to be related to the operative procedure infection involves any part of the body, excluding the skin incision, fascia, or muscle layers, that is opened or manipulated during the operative procedure and patient has at least one of the following: a. purulent drainage from a drain that is placed through a stab wound into the organ/space b. organisms isolated from an aseptically obtained culture of fluid or tissue in the organ/space c. an abscess or other evidence of infection involving the organ/space that is found on direct examination, during reoperation, or by histopathologic or radiologic examination d. diagnosis of an organ/space SSI by a surgeon or attending physician.

Further classifications

According to the etiology Primary SSI :the wound is the primary site for infection Secondary SSI :infection arise following a complication that is not directly related to the wound According to the time Early with in 30 days Intermediate 1-3 months Late more than 3 months According to Severity Minor SSI :discharge without cellulites or deep tissue destruction Major SSI :pus discharge with tissue breakdown, partial or total dehiscence or systemic illness

Source of SSI Pathogens

Endogenous flora of the patient Operating theater environment Hospital personnel (doctors/nurses/staff) Seeding of the operative site from distant focus of infection (prosthetic device, implants)

Pathogenesis of SSI

Relationship equation Dose of bacterial contamination x Virulence Resistance of host


SSI RISK

Risk factors

surgical factors Type of procedure Degree of contamination Duration of operation Urgency of operation patient-specific factors. Patient-specific factors can be further defined as either local High bacterial load Wound hematoma Necrotic tissue Foreign body Obesity

systemic Advanced age Shock Diabetes Malnutrition Alcoholism Steroids Chemotherapy Immuno-compromise

Wound Classificationaccording to the degree of contamination

Determinants of the infection
Every surgical site is contaminated by bacteria at the end of the procedure, few become clinically infected. Four important determinants lead to either uneventful wound healing or SSI. Inoculums of the bacteria Virulence of the bacteria Effects of microenvironment Integrity of host defenses (Innate and acquired )

1. Inoculum of the bacteria

Sources:Air in operation roomInstrumentsSurgeons and staffPatient’s flora. Largest inoculum is from areas that are heavily colonized e.g. bowel, female GUT, diseased biliary tractThis factor is modifiable

2. Virulence of the bacteria

The more virulence the bacteria, the greater probability of infection Coagulase positive staph Virulent strain of perfiringens and group A streptococi E coli Bacteroids This factor can not easily be controlled by preventive strategies because it is intrinsic to the procedural site and the type of bacteria that already colonize the patient

3. Effects of microenvironment

The following factors in the microenviroment of the wound predispose to SSI Necrotic tissue Hb at the surgical site FB, drains Dead space with in the surgical site Surgical techniques

4. Integrity of host defenses

Innate host defense deficiency Acquired host defense deficiency Shock and hypoxia Transfusion Chronic illness Hypoalbuminaemia Malnutrition Hypothermia Hyperglycemia Corticosteroids Obesity Nicotine use chemotherapy

Prevention of SSI

Preoperative planning Intra operative technique Preventive antibiotic therapy Enhancement of host defense

1. Preoperative planning

Control preexisting infection of patient Postpone the operation if open skin wound or hand infection of surgeon present Decrease preoperative hospitalization period Shower and scrub the surgical site with antiseptic soap the evening prior to operation Clipping the hair from surgical site before the operation

2. Intra operative technique

Skin preparation Caps, masks gowns, surgical gloves Sterilization of the instruments Gentle handling of tissue Good haemostasis
Avoid dead space Insert drains through separate stab incision Leave skin and subcutaneous tissue open if dirty Sterile dressing Topical ointments



3. Preventive antibiotic therapy4. Enhancement of host defenseIncrease oxygen deliveryOptimizing core body temperatureBlood glucose controlCorrect any coexisting condition e.g malnutrition, anemia……