5.3 Surgical Wounds, Infections & Tetanus Prophylaxis

5.3 Surgical Wounds, Infections & Tetanus Prophylaxis

Core Clinical Rule: In surgical wound management, antibiotic prophylaxis can never compensate for poor surgical technique, tissue devitalization, or inadequate wound debridement. When post-operative fever manifests on postoperative Day 5, evaluate the wound directly: the treatment of a surgical site infection is mechanical drainage and opening of the wound, not escalating systemic antibiotics. In tetanus prophylaxis, whenever a patient presents with a tetanus-prone/contaminated wound and an incomplete (< 3 doses) or unknown immunization history, you must administer both Tetanus Toxoid (TT/Td) and Tetanus Immunoglobulin (TIG) using separate syringes at separate anatomical sites.

Surgical site infections (SSIs) represent the most frequent nosocomial infection among surgical patients across sub-Saharan Africa, prolonging hospital stays, escalating healthcare expenditures, and driving surgical mortality. Concurrently, traumatic wounds contaminated by soil or animal feces carry high lethality if tetanus prophylaxis protocols are breached. Mastering surgical wound classification, postoperative fever differential diagnosis, and evidence-based tetanus prevention is foundational for clinical officers practicing in district and referral hospitals.

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1. Surgical Wound Classification & Infection Prevention Bundles

The CDC and American College of Surgeons (ACS) classify surgical wounds based on the intrinsic degree of microbial contamination at the time of operation. This classification predicts the baseline risk of surgical site infection and dictates the appropriate antibiotic strategy.

Evidence-Based SSI Prevention Bundle

To reduce surgical site infections, the World Health Organization (WHO) and Kenya Ministry of Health mandate adherence to a strict perioperative bundle:

1. Preoperative Chlorhexidine Bathing: Patients should bathe with soap or chlorhexidine the night before surgery.
2. Hair Removal: Avoid razor shaving! Shaving causes microscopic dermal abrasions that harbor bacterial proliferation. If hair must be removed, use electric clippers with disposable heads immediately prior to surgery.
3. Surgical Skin Preparation: Use an alcohol-based solution of chlorhexidine gluconate ($2%$) in $70%$ isopropyl alcohol. Alcohol-chlorhexidine provides superior residual antibacterial action compared to aqueous povidone-iodine.
4. Antimicrobial Prophylaxis Timing: Administer intravenous prophylactic antibiotics (e.g., Cefazolin $1\text{ to }2\text{ g}$ IV; add Metronidazole $500\text{ mg}$ IV for colorectal or pelvic surgery) within 60 minutes prior to surgical incision (or within 120 minutes for vancomycin/fluoroquinolones). Re-dose intraoperatively if the operation exceeds two half-lives of the drug ($> 3\text{ to }4\text{ hours}$ for cefazolin) or if blood loss exceeds $1,500\text{ mL}$. Discontinue prophylaxis within 24 hours post-operatively.
5. Maintenance of Perioperative Normothermia: Maintain core body temperature $\ge 36^\circ\text{C}$ using warm air blankets. Hypothermia induces peripheral vasoconstriction, reduces tissue oxygen delivery, impairs neutrophil phagocytosis, and triples the risk of SSI.
6. Perioperative Glycemic Control: Maintain blood glucose $< 11.1\text{ mmol/L}$ ($< 200\text{ mg/dL}$) in both diabetic and non-diabetic surgical patients.

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2. Post-Operative Fever Timeline: "The 5 Ws"

Postoperative fever ($T \ge 38.0^\circ\text{C}$) is a common clinical dilemma. The timing of fever onset relative to the day of operation provides the single most reliable diagnostic clue to its underlying etiology.

+-----------------------------------------------------------------------------------+
|                    THE CLASSIC 5 Ws OF POSTOPERATIVE FEVER                        |
+-----------------------------------------------------------------------------------+
| DAY 1–2: WIND       | Atelectasis (alveolar collapse from shallow breathing,      |
|                     | hypoventilation, opioid use, thoracic/abdominal splinting).  |
+---------------------+-------------------------------------------------------------+
| DAY 3:   WATER      | Urinary Tract Infection (catheter-associated UTI secondary  |
|                     | to indwelling Foley catheters).                             |
+---------------------+-------------------------------------------------------------+
| DAY 5:   WOUND      | Surgical Site Infection (superficial or deep incisional SSI;|
|                     | classical presentation 5 to 7 days post-surgery).           |
+---------------------+-------------------------------------------------------------+
| DAY 7:   WALKING    | Venous Thromboembolism (Deep Vein Thrombosis / Pulmonary    |
|                     | Embolism driven by surgical stasis and hypercoagulability). |
+---------------------+-------------------------------------------------------------+
| DAY > 7: WONDER     | Drug-Induced Fever (adverse reaction to antimicrobials,     |
|          DRUGS      | heparin, or anticonvulsants) or Deep Abscess/Leak.          |
+-----------------------------------------------------------------------------------+

In-Depth Clinical Evaluation by Postoperative Day

• Postoperative Days 1–2: "Wind" (Atelectasis):
  • Mechanism: General anesthesia, muscle relaxants, diaphragmatic splinting, and opioid analgesics cause shallow tidal breathing, leading to collapse of lung alveoli in dependent lung bases.
  • Clinical Findings: Low-grade fever ($38.0^\circ\text{C}$ to $38.5^\circ\text{C}$), mild tachypnea, bronchial breath sounds, and fine end-expiratory crackles at both lung bases. Chest radiograph may show basilar discoid atelectasis or be entirely normal.
  • Management: Chest physiotherapy, incentive spirometry (10 breaths every hour while awake), early out-of-bed ambulation, and adequate multimodal analgesia to abolish painful abdominal splinting. Antibiotics are NOT indicated for uncomplicated atelectasis.
• Postoperative Day 3: "Water" (Urinary Tract Infection):
  • Mechanism: Catheter-associated urinary tract infection (CAUTI) following prolonged indwelling urethral catheterization. Biofilm formation along the catheter allows Escherichia coli, Klebsiella, or Enterococcus colonization.
  • Clinical Findings: Fever, suprapubic tenderness, dysuria, frequency, cloudy or malodorous urine.
  • Management: Remove the Foley catheter promptly. Obtain clean-catch or catheter-specimen urine for microscopy, culture, and sensitivity. Initiate targeted antimicrobial therapy (e.g., Nitrofurantoin, Ciprofloxacin, or Ceftriaxone depending on local hospital susceptibility patterns).
• Postoperative Day 5: "Wound" (Surgical Site Infection):
  • Mechanism: Microbial proliferation within the surgical incision, most commonly Staphylococcus aureus (including MRSA), Enterobacteriaceae, or anaerobes.
  • Clinical Findings: Pain out of proportion, spreading perilesional erythema, localized edema, marked warmth, wound induration, wound dehiscence, or purulent exudate draining between sutures/staples.
  • Management: Immediate mechanical opening of the wound. Remove skin sutures or staples over the area of maximum fluctuance. Gently probe the incision with sterile forceps, evacuate all purulence and infected hematoma, debride non-viable fascial margins, take a deep pus swab for Gram stain and culture, irrigate generously with warm normal saline, and pack loosely with saline-moistened sterile gauze for healing by secondary intention. Systemic antibiotics are indicated only if spreading cellulitis ($> 5\text{ cm}$) or systemic signs of sepsis (hypotension, marked tachycardia) are present.
• Postoperative Day 7: "Walking" (Deep Vein Thrombosis & Pulmonary Embolism):
  • Mechanism: Virchow's Triad—venous stasis (prolonged intraoperative and postoperative immobilization), endothelial injury (pelvic/lower extremity surgery), and hypercoagulability (surgical stress response).
  • Clinical Findings: Unilateral lower extremity swelling (calf circumference difference $> 3\text{ cm}$), dull aching calf pain, localized warmth, tenderness along the deep venous system. If complicated by Pulmonary Embolism (PE): sudden dyspnea, pleuritic chest pain, tachypnea, tachycardia ($S_1Q_3T_3$ pattern on ECG), and acute hypoxemia.
  • Management: Diagnostic compression venous ultrasonography or CT pulmonary angiogram (CTPA). Initiate therapeutic anticoagulation with Low-Molecular-Weight Heparin (LMWH, e.g., Enoxaparin $1\text{ mg/kg}$ subcutaneous 12-hourly) transitioned to oral anticoagulants.
• Postoperative Day $> 7$: "Wonder Drugs" & Hidden Complications:
  • Mechanism: Hypersensitivity reactions to medications (beta-lactam antibiotics, sulfonamides, heparin-induced fever, phenytoin) or deep intra-abdominal occult complications (anastomotic dehiscence, pelvic/subphrenic abscess).
  • Clinical Findings: Persistent spiking fevers in a patient who appears otherwise well, accompanied by peripheral eosinophilia or maculopapular drug rash. If intra-abdominal leak: persistent tachycardia, localized peritonitis, paralytic ileus.
  • Management: Discontinue suspect medications. If deep collection or leak is suspected, perform an abdominal contrast-enhanced CT scan for percutaneous drainage or re-laparotomy.

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3. Tetanus Prophylaxis Protocol

Tetanus is an acute, spastic neurological disease caused by the potent exotoxin produced by Clostridium tetani—an obligate anaerobic, Gram-positive, spore-forming bacillus ubiquitously distributed in soil, street dust, animal manure, and human feces.

Pathophysiology & Tetanospasmin Action

1. Spores enter breached skin via puncture wounds, lacerations, burns, or contaminated surgical incisions.
2. In the presence of anaerobic conditions (devitalized tissue, foreign bodies, ischemia, or co-existing aerobic bacterial infection consuming oxygen), spores germinate into vegetative bacilli that multiply locally without systemic tissue invasion.
3. The bacilli produce two exotoxins: tetanolysin (tissue hemolysin) and tetanospasmin (a potent zinc-dependent endopeptidase neurotoxin).
4. Tetanospasmin binds to peripheral motor nerve terminals, enters the axon via endocytosis, and migrates via retrograde intra-axonal transport to the spinal cord and brainstem.
5. Within the central nervous system, tetanospasmin cleaves synaptobrevin (VAMP), an essential vesicle-associated membrane protein. This cleaving prevents the exocytic release of inhibitory neurotransmitters (GABA and Glycine) from presynaptic inhibitory interneurons (Renshaw cells).
6. Deprived of central inhibitory control, motor neurons fire uncontrollably at high frequency, resulting in agonizing reflex muscle spasms: trismus ("lockjaw"), risus sardonicus (sardonic grin), opisthotonos (arched back), laryngospasm, and violent generalized spasms triggered by minimal auditory or visual stimuli. Autonomic hyperactivity triggers labile hypertension, tachycardia, hyperpyrexia, and cardiac arrhythmias.

Wound Risk Stratification

+-----------------------------------------------------------------------------------+
|                         WOUND CLASSIFICATION FOR TETANUS                          |
+-----------------------------------+-----------------------------------------------+
| CLEAN, MINOR WOUNDS               | TETANUS-PRONE / CONTAMINATED WOUNDS           |
+-----------------------------------+-----------------------------------------------+
| - Superficial, sharp incised cuts | - Wounds contaminated with soil, feces,       |
|   (e.g., clean kitchen knife,      |   dirt, manure, or saliva                     |
|   clean glass)                    | - Puncture wounds (nails, wooden splinters)   |
| - Minimal tissue loss             | - Animal or human bites                       |
| - No devitalized or crushed tissue| - Crush injuries, avulsions, blast injuries   |
| - Presentation < 6 hours post-    | - Wounds with devitalized necrotic tissue     |
|   injury                          | - Compound (open) fractures                   |
| - Devoid of contaminants          | - Thermal, chemical, or electrical burns      |
|                                   | - Any wound presenting after a delay > 6 hours|
+-----------------------------------+-----------------------------------------------+

National Tetanus Prophylaxis Algorithm (Kenya MOH / WHO / CDC)

Every traumatic wound requires systematic evaluation of two parameters: (1) The nature of the wound (clean minor vs tetanus-prone), and (2) The patient's prior tetanus immunization history.

Mandatory Administration & Surgical Principles

1. Separate Syringes, Separate Sites: When administering both Tetanus Toxoid (active immunity) and Tetanus Immunoglobulin (passive immunity), you must inject them using separate syringes at completely different anatomical sites (e.g., TT in the right deltoid and TIG in the left deltoid or anterolateral thigh). Never mix TT and TIG in the same syringe or inject them into the same limb, as the circulating antibodies will bind and neutralize the vaccine toxoid, rendering the active vaccination entirely useless.
2. TIG Dosing: The standard prophylactic dose of Human Tetanus Immunoglobulin is $250\text{ IU}$ IM. Increase to $500\text{ IU}$ IM if the wound is heavily contaminated with soil/feces, presents after $> 24\text{ hours}$, or is associated with extensive tissue necrosis.
3. Thorough Surgical Debridement: Pharmacological prophylaxis is useless if non-viable tissue remains. Vigorously irrigate wounds with copious normal saline under pressure, debride all non-viable tissue, excise foreign bodies, and leave heavily contaminated wounds open to prevent the formation of an anaerobic environment.