Surgical site infections are the second most common types of healthcare associated infections (HAIs). A surgical site is the incision made by the surgeon during a surgical procedure as well as any manipulated surrounding tissue. Surgical site infections may be caused by intrinsic factors (related to the patient) or extrinsic factors (related to the environment or the equipment used). They develop from 2 to 3 days following surgery or during the wound healing period (up to 3 weeks post-surgery).
Pathogenesis of Surgical Site Infections
SSIs develop through an interaction between microorganisms and host, which is also affected by the surgeon and environment. All surgical wounds have microorganisms, including bacteria, but not all develop a clinical infection, since innate host defenses can be very efficient in eliminating contaminants within the surgical site. If however the concentration of microorganisms in the wound is very high, developing a surgical site infection becomes quite possible.
Risk Factors for Surgical Site Infections
Patient-Related Risk Factors:
- increasing age
- diabetes
- obesity
- smoking
- immunosuppressants
- staphylococcus aureus carriage
- distant infection focus
- malnutrition
Pre-operative Risk Factors:
- length of pre-operative stay
- antibiotic prophylaxis
- hair removal technique
Operative Risk Factors:
- wound classification
- operative technique
- degree of tissue trauma
- prolonged duration of surgery
- traffic intensity in the operating room
- foreign body presence
Increasing Risk for SSI
intact skin > intact mucous membrane > broken skin or mucous membrane > foreign body implant > foreign body from outside to inside of the body
(foreign body implant eg. prosthetic)
Superficial Incisional SSI:
- purulent drainage from superficial incision with or without lab confirmation
- pain OR swelling OR erythema OR heat at incision site (at least one)
- surgeon deliberately opens incision (unless culture-negative)
Deep Incisional SSI:
- abscess involving deep incision found during radiological exam, direct exam or re-operation
- deep incision deliberately opened by surgeon when patient has at least one of the following: fever, localised pain, tenderness (unless culture-negative)
- purulent drainage found during deep incision but not from organ/space component
- teach patient to monitor for SSIs for 90 days post-operation, and give contact details in case a SSI is suspected
Organ/Space SSI:
Involves organs or spaces other than the surgical incision site such as:
- Mediastinitis
- Endocarditis
- Osteopmyelitis
- Meningitis
- Ventriculitis
- Intra-abdominal
Organ/Space SSI should also include at least one of the following: purulent drainage, organisms isolated from an aseptically obtained culture of fluid or tissue in the organ/space, abscess or other evidence of infection.
Wound Healing
Phases of Wound Healing
Surgical Wound Classification
Post-Discharge Surveillance for Surgical Site Infections
Post-discharge surveillance for surgical site infections are important for early detection of SSIs. Following surgery, the nurse should advise the patient to watch out for signs of SSIs for 30 days post-operation, and give contact details the patient should use in case a SSI is suspected.
Post-discharge SSI surveillance methods include:
- medical records review
- admission
- readmission
- patient charts for SSI signs and symptoms
- lab, imaging and other diagnostic tests
- clinician notes
- questionaires
- patient surveys (may be performed through phone or mail)
If an SSI is suspected, or if there is no sign of healing, or if there is unexpected wound healing process deterioration, a specimen should be collected as soon as possible, ideally prior to starting antibiotic treatment.
Organisms Causing SSIs
- Staphylococcus aureus
- Coagulase-negative staphylococci
- Gram negative bacilli
- Anaerobes
- group B streptococci
WHO Guidelines on Surgical Site Infections
Surgical Handrubbing Technique
Hyperglycaemia and Surgical Site Infections
Hyperglycaemia is associated with an increased risk of developing surgical site infections, especially in the post-operative period. Early post-operative glycaemic control should reduce the incidence of surgical site infections eg. diabetic protocol.
Pre-operative Hair Removal
Unless the presence of hair at the surgery site may interfere with the surgery itself, hair should not be removed. However, if required, hair should be removed with the use of surgical hair clippers with disposable heads. This should be done on the ward at the latest time possible – NEVER at the theatre due to potential contamination of the sterile field. Shavers should NOT be used since these create micro-abrasions in the skin, increasing the of infection.
Following hair removal, patients need to shower with 4% chlorhexidine solution.
Normothermia
Hypothermia increases the risk of developing a SSI since it causes physiological changes, impairs the immune system, causes subcutaneous vasoconstriction, and tissue hypoxia at the incision site. Additionally, hypothermia increases the risk of bleeding, risk of haematoma, and risk of needing a blood transfusion. Thus, pre-operative and intraoperative normothermia should be targeted – ideal temperature is that of 36°C or more.
MRSA and Surgical Site Infections
MRSA carriage increases the risk of developing a SSI. For this reason, patients are screened prior to surgical procedures such as Coronary Artery Bypass Graft, Aortic Valve Replacement, Total Knee Replacement, Total Hip Replacement, cardiac implants, renal catheter insertions, and central venous catheters.
If MRSA is cultivated, decolonisation treatment in the form of washes and mupirocin nasal ointment is required. The patient is screened three times for MSSA (methicillin-susceptible Staphylococcus aureus) prior to the procedure.
Preoperative Washing
Preoperative bathing or showering should aim to reduce skin bacterial load, leading to a reduction in the development of endogenous surgical site infections.
4% Chlorhexidine Solution for MRSA Colonisation: 4% Chlorhexidine solution is a topical antibiotic commonly used as a skin cleanser prior to surgery due to its protective effects against gram-positive and gram-negative organisms, facultative anaerobes, aerobes, and yeast. This is ideal if MRSA colonisation is present.
2% Chlorhexidine Solution for Prolonged/Deep Surgeries: Skin disinfection with 2% Chlorhexidine is enough in the case of prolonged surgery or deep surgery.
Plain Soap for Minor Surgeries: For other minor surgeries, washing with plain soap is enough.
NOTE: Make sure the patient stays warm prior to being operated upon, since this reduces the chance of developing SSIs.
Prophylactic Use of Antibiotic
CHOICE OF ANTIBIOTIC TREATMENT
Antibiotic treatment choice for prophylactic use should be based on the wound contamination level and efficacy against expected pathogens related to the specific surgery being performed.
TIMING
First dose of prophylactic antibiotic should be given 60-120 minutes prior to surgery being performed, as this ensures bactericidal concentration in serum and tissues from incision until closure. Additional doses may be required for longer surgeries.
DURATION
Unnecessary continuation of antibiotic treatment may contribute to the ever-growing problem of antibiotic resistance.
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Claire is keen about public education on health-related subjects as well as holistic patient-centered care. She is also passionate about spreading awareness on the negative effects that domestic abuse leaves on its victims’ mental, emotional, social and physical wellbeing.
Claire aspires to continue studying following completion of her Nursing Degree, because she truly believes in lifelong education.
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