SURGICAL WOUND INFECTION

Dr. Hatem ElGohary

Lecturer of General Surgery MD, MRCS

PHYSIOLOGY Micro-organisms are normally prevented from causing

infection in tissues by intact epithelial surfaces. These are broken down in trauma and by surgery.

Protective mechanisms against infection can be

divided into:

• Chemical: low gastric pH;

• Humoral: antibodies, complement and

opsonins;

• Cellular: phagocytic cells, macrophages,

killer lymphocytes.

Risk factors for increased risk of wound infection

■ Malnutrition (obesity, weight loss)

■ Metabolic disease (diabetes, uraemia, jaundice)

■ Immunosuppression (cancer, AIDS, steroids,

chemotherapy and radiotherapy)

■ Colonisation and translocation in the gastrointestinal

tract

■ Poor perfusion (systemic shock or local ischaemia)

■ Foreign body material

■ Poor surgical technique (dead space, haematoma)

CLINICAL PICTURE

Symptoms

Fever

Throbbing pain

Pus or watery discharge

Signs

Redness

excessive swelling in the wound

tenderness in the wound area

Wound Classification

Class I (Clean)

Operative wound clean, no inflammation,

Respiratory, gastrointestinal and genitor-

urinary tracts not entered.

Examples: Thyroidectomy, mastectomy.

Infection rate: 1-2%

Class II (Clean Contaminated)

Operative wound clean-contaminated

Gastrointestinal, respiratory or genitor-urinary tracts entered without significant spillage

Examples: Appendectomy, cholecystectomy.

Infection rate: 20-30 %

Class III (Contaminated)

Operative wound contaminated

Gross spillage from the gastrointestinal tract, genito-urinary or biliary tracts.

Example: Colectomy.Infection rate: up to 60%

Class IV (Dirty Infected)

Operative wound dirty

Traumatic wound from dirty source, Fecal contamination, Foreign body.

Examples: Drainage of Abscess

Debridement of Diabetic foot.Infection rate: more than 60%.

Types of localized infectionAbscess (Acute suppurative inflammation +Localized Collection of pus). Caused by Staphylococcus aureus Pus (dead and dying white blood cells). Surrounded by Pyogenic membrane. C/P: Redness, Hotness, Tenderness

and edema. Treatment: Incision and drainage.

Cellulitis and Lymphangitis (non suppurative diffuse inflammation).

Caused by β-haemolytic streptococci. C/P: Redness, Hotness, Tenderness and

edema. Treatment: Antibiotics.

Specific wound infectionsGas gangrene Caused by C. perfringens. Gram-positive,

anaerobic bacilli found in soil and faeces. Common in wounds containing necrotic or

foreign material. C/P: severe local wound pain and crepitus (gas in

the tissues). X-ray: Gas in tissues. Treatment: 1.Intravenous penicillin.

2.Aggressive debridement of

affected tissues.

Tetanus

Caused by Clostridium tetani (anaerobic, Gram-positive bacterium).

common in traumatic civilian or military wounds.

Mechanism: release of the exotoxin tetanospasmin, which affects myo-neural junctions and the motor neurones of the anterior horn of the spinal cord.

C/P: prodromal period, leads to spasms in the distribution of the motor nerves of the face followed by the development of severe generalised motor spasms respiratory arrest and death.

Treatment:

1. Prophylaxis with tetanus toxoid is the

best preventative treatment

2. Debridement of the wound may need to

be performed.

3. Antibiotic treatment with benzylpenicillin

4. Ventilation in respiratory spasm.

TREATMENT OF SURGICAL INFECTION

Prophylaxis1.Prophylactic antibiotics Maximal blood and tissue levels should be

present at the time incision is made Givin at induction of anaesthesia. The choice of an antibiotic depends on the

expected spectrum of organisms likely to

be encountered. Patients with known valvular disease of

the heart, prophylactic antibiotics during dental, urological or open viscus surgery.

2.Preoperative preparation

Short preoperative hospital stay lowers the risk of acquiring infection.

Medical staff should always wash their hands between patients.

personal hygiene is vital. Staff with open, infected skin lesions should

not enter the operating theatres. Antiseptic baths. Preoperative shaving immediate before

surgery.

3.Scrubbing and skin preparation Aqueous antiseptics should be used,

and the scrub should include the nails, washing to the elbows e.g. Betadine or alcohol.

4.Intra-Operative care

Numbers of staff in the theatre and movement in and out of theatre should be kept to a minimum.

dead spaces and haematomas should be avoided and the use of diathermy kept to a minimum.

Postoperative care of wounds Tissue or pus for culture should be taken

before antibiotic cover is started.

The choice of antibiotics is empirical until sensitivities are available.

Wounds are best managed by delayed primary or secondary closure.

The use of Anti-microbials

The use of antibiotics for the treatment of established surgical infection ideally requires recognition and determination of the sensitivities of the causative organisms.

choice being empirical and later modified depending on microbiological findings.

Drainage of pus should not be delayed.

Types of antibiotics use

A narrow-spectrum antibiotic may be used to treat a known sensitive infection.

Combinations of broad-spectrum antibiotics can be used when the organism is not known.

Precautions In HIV Patients• Use of a full face mask ideally, or protective spectacles.

• use of fully waterproof, disposable gowns and drapes

• boots to be worn, not clogs, to avoid injury from dropped

sharps;

• double gloving needed

• allow only essential personnel in theatre;

• avoid unnecessary movement in theatre;

• respect is required for sharps, with passage in a kidney dish;

• a slow meticulous operative technique is needed with minimised

bleeding.