2. Surgical infection and antibiotics

 

Surgical infection and antibiotics — exam master note

For the exam, remember this central rule:

Surgical infection is not treated by antibiotics alone.
The real treatment is:

Resuscitation + source control + correct antibiotics + repeated reassessment.

A patient with pus, necrosis, leak, perforation, dead tissue, foreign body, or infected collection needs surgery/drainage/debridement. Antibiotics only support that process.

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1. What is surgical infection?

A surgical infection is infection related to trauma, an operation, a wound, a surgical organ system, or a postoperative complication.

Main examples:

Wound/SSI

Superficial incisional, deep incisional, organ-space infection.

Soft tissue infection

Cellulitis, abscess, necrotizing fasciitis, gas gangrene, Fournier gangrene.

Intra-abdominal infection

Appendicitis, perforated ulcer, diverticulitis, peritonitis, anastomotic leak, abscess.

Biliary infection

Acute cholecystitis, cholangitis, liver abscess.

Device/prosthesis infection

Mesh, vascular graft, joint prosthesis, cardiac device, central line.

Traumatic wound infection

Open fractures, contaminated wounds, bites, crush injuries.

CDC/NHSN classifies SSI by the deepest involved level: superficial incisional, deep incisional, or organ/space, and surveillance is usually based on a 30- or 90-day period depending on the procedure and tissue level. (CDC)

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2. The basic pathogenesis

Infection develops when:

Bacterial load × virulence > host defence + tissue perfusion

High-yield factors:

Bacterial factors

Large inoculum, virulent organism, polymicrobial contamination, toxin production, biofilm formation.

Local wound factors

Dead tissue, hematoma, seroma, foreign body, sutures, prosthesis, poor blood supply, tension, dead space.

Host factors

Diabetes, obesity, malnutrition, smoking, steroid use, immunosuppression, old age, renal failure, jaundice, shock, hypoxia, hypothermia, anaemia.

Operation factors

Emergency surgery, long operation, contamination, bowel spillage, poor haemostasis, excessive tissue handling, drain misuse, prosthetic material.

Exam line:
A foreign body dramatically lowers the bacterial inoculum needed to cause infection.

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3. Wound classification

You must know this. It decides prophylaxis, infection risk, and closure method.

Clean wound

No inflammation.
No entry into respiratory, alimentary, genital, or urinary tract.
No break in sterile technique.

Examples: elective hernia repair, thyroidectomy, breast surgery.

Clean-contaminated wound

Controlled entry into respiratory, GI, biliary, genital, or urinary tract without major spillage.

Examples: elective cholecystectomy, elective bowel surgery with preparation, gastrectomy.

Contaminated wound

Major break in sterile technique, gross GI spillage, fresh traumatic wound, acute non-purulent inflammation.

Examples: traumatic open wound, perforated appendix without pus, bowel spillage.

Dirty/infected wound

Existing infection, pus, perforated viscus, faecal contamination, devitalized tissue, delayed traumatic wound.

Examples: faecal peritonitis, abscess drainage, gangrenous perforated bowel.

NICE uses the same conceptual classification and defines dirty/infected wounds as those with perforated viscus, pus, delayed contaminated trauma, faecal contamination, or devitalised tissue. (NICE)

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4. Common organisms by surgical site

Skin and clean wounds

Staphylococcus aureus
Streptococcus pyogenes
Coagulase-negative staphylococci, especially with prosthetic material.

GI and colorectal surgery

Gram-negative rods: E. coli, Klebsiella, Enterobacter
Anaerobes: Bacteroides fragilis
Enterococcus may matter in healthcare-associated or high-risk intra-abdominal infection.

Biliary tract

E. coli, Klebsiella, Enterococcus, anaerobes less dominant unless severe/obstructed/previous instrumentation.

Urology

E. coli, Klebsiella, Proteus, Pseudomonas in catheterised or hospital-acquired cases.

Necrotizing infections

Type 1: polymicrobial, mixed aerobes and anaerobes.
Type 2: Group A Streptococcus ± Staphylococcus aureus.
Clostridial myonecrosis: Clostridium species.

Hospital/ICU/postoperative sepsis

Enterobacterales, Pseudomonas, Acinetobacter, MRSA, Enterococcus, Candida in selected high-risk patients.

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5. Surgical site infection: clinical diagnosis

Look for:

Local signs:

Pain, redness, warmth, swelling, tenderness, wound discharge, pus, wound dehiscence, cellulitis.

Systemic signs:

Fever, tachycardia, hypotension, confusion, leukocytosis/leukopenia, raised CRP/procalcitonin, lactate rise.

Deep/organ-space clues:

Persistent fever after surgery, ileus, abdominal pain, tachycardia, sepsis, drain output becoming purulent/faeculent/bilious, raised inflammatory markers, failure to recover.

Important exam timing trap:

Very early severe wound pain within 24–48 hours after surgery suggests Group A streptococcal infection or clostridial infection, not ordinary SSI.

Ordinary wound infection usually appears later, often around postoperative day 5–7.

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6. Prevention of surgical infection

Preoperative prevention

Correct modifiable risks:

Control diabetes and hyperglycaemia.
Treat remote infection before elective surgery.
Optimise nutrition.
Stop smoking if possible.
Correct anaemia and hypoxia where possible.
Avoid unnecessary preoperative shaving.

NICE recommends bathing/showering with soap before surgery, avoiding routine hair removal, and using electric clippers rather than razors if hair must be removed. (NICE)

Intraoperative prevention

Key points:

Aseptic technique.
Correct skin preparation.
Correct antibiotic prophylaxis.
Gentle tissue handling.
Good haemostasis.
Avoid dead space.
Remove devitalised tissue.
Maintain normothermia.
Maintain oxygenation and perfusion.
Minimise operation time.
Use drains only when indicated.

NICE recommends antiseptic skin preparation immediately before incision and lists alcohol-based chlorhexidine as first choice unless contraindicated or near mucosa; it also emphasises maintaining temperature, oxygenation, and perfusion during surgery. (NICE)

Postoperative prevention

Aseptic dressing change.
Early recognition of infection.
Avoid unnecessary opening of clean wounds.
Remove unnecessary lines, catheters, drains.
Do not prolong prophylactic antibiotics “because drain is there”.

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7. Antibiotic prophylaxis

This is one of the highest-yield exam areas.

Purpose

Antibiotic prophylaxis is given to prevent infection from predictable contamination during surgery.

It is not treatment of established infection.

When to give prophylaxis

Give prophylaxis for:

Clean surgery with prosthesis or implant.
Clean-contaminated surgery.
Contaminated surgery.

Do not routinely give prophylaxis for clean, uncomplicated, non-prosthetic surgery. NICE specifically recommends prophylaxis before clean surgery involving prosthesis/implant, clean-contaminated surgery, and contaminated surgery, but not routinely for clean non-prosthetic uncomplicated surgery. (NICE)

Dirty wound

Dirty/infected wound needs therapeutic antibiotics, not just prophylaxis.

Example: perforated sigmoid colon with faecal peritonitis.

Timing

Give IV antibiotic so tissue levels are adequate at incision.

General rule:

Within 60 minutes before incision.

Vancomycin and fluoroquinolones need longer infusion, so they should begin within 120 minutes before incision. ASHP recommends starting most antimicrobials within 60 minutes before incision, while vancomycin and fluoroquinolones should begin within 120 minutes because of infusion time. (ASHP)

Tourniquet surgery

Give antibiotic before tourniquet inflation.

Redosing

Redose if:

Operation is prolonged beyond about two half-lives of the antibiotic.
Major blood loss occurs.
Massive fluid replacement occurs.

ASHP recommends intraoperative redosing when the operation exceeds two half-lives of the drug or when there is excessive blood loss, and the redosing interval is measured from the time of the preoperative dose. (ASHP)

Duration

Most surgical prophylaxis is:

Single dose or less than 24 hours.

Do not continue prophylaxis for 3–5 days without indication. ASHP notes that postoperative antimicrobial administration is not necessary for most procedures and that prophylaxis should generally be less than 24 hours. (ASHP)

Common prophylaxis patterns

Clean skin/prosthetic surgery:

Cefazolin or equivalent anti-staphylococcal cephalosporin.

Colorectal surgery:

Cephalosporin + metronidazole, or agent covering Gram-negative rods and anaerobes.

Biliary surgery:

Cephalosporin-based regimen, broader if severe inflammation, obstruction, elderly, jaundice, previous instrumentation.

Urology:

Depends on urine culture and local Gram-negative resistance.

MRSA colonisation/high-risk:

Consider vancomycin, usually with additional Gram-negative cover if required by procedure. Vancomycin is not routine for everyone; ASHP says routine vancomycin prophylaxis is not recommended, but it may be considered for MRSA colonisation/high-risk or institutional MRSA clusters. (ASHP)

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8. Treatment principles of established infection

Use this framework in viva/OSCE:

Step 1 — Assess severity

ABCDE.
Look for sepsis or septic shock.
Check mental status, BP, urine output, lactate, respiratory distress.

Step 2 — Identify the source

Wound?
Abdomen?
Chest?
Urine?
Line?
Biliary?
Anastomotic leak?
Abscess?

Step 3 — Take cultures

Blood cultures if septic.
Pus/tissue sample is better than superficial swab.
Urine/sputum/drain fluid depending on source.

But do not delay antibiotics in septic shock.

Step 4 — Start empiric antibiotics

Cover likely organisms based on:

Site of infection.
Community vs hospital-acquired.
Previous antibiotics.
Known colonisation.
Renal function.
Allergy.
Local resistance pattern.

Step 5 — Source control

Drain abscess.
Open infected wound.
Debride necrotic tissue.
Remove infected foreign body if needed.
Repair perforation/leak.
Divert faecal stream if needed.
Remove infected catheter.
Drain biliary obstruction.

Step 6 — Reassess and de-escalate

Review at 24–48 hours.
Check cultures.
Narrow spectrum.
Stop antibiotics if infection unlikely.
Decide duration.

Surviving Sepsis recommends immediate antibiotics, ideally within 1 hour, for septic shock or high-likelihood sepsis; it also recommends daily assessment for de-escalation, shorter duration after adequate source control, and rapid identification/intervention for sources needing source control. (Society of Critical Care Medicine (SCCM))

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9. Source control

This is the soul of surgical infection.

Antibiotics cannot reliably treat:

Pus under pressure.
Necrotic tissue.
Foreign body biofilm.
Faecal contamination.
Anastomotic leak.
Obstructed infected system.
Devitalised bowel.
Infected gallbladder with obstruction.

Examples

Abscess → incision and drainage.
Empyema → chest tube/VATS.
Cholangitis → biliary drainage/ERCP.
Faecal peritonitis → laparotomy/laparoscopy, lavage, control perforation.
Infected necrosis → drainage/necrosectomy when indicated.
Infected central line → remove line.
Necrotizing fasciitis → urgent radical debridement.

For complicated intra-abdominal infection, modern guidance supports short antibiotic duration after adequate source control; the 2024 WSES-linked recommendations state that 4 days fixed-duration therapy is appropriate after adequate source control, and persistent illness after 7 days should trigger re-investigation rather than simply extending antibiotics. (Springer)

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10. Abscess

Classic surgical rule:

Ubi pus, ibi evacua — where there is pus, evacuate it.

Clinical features:

Painful fluctuant swelling.
Redness, warmth.
Tenderness.
Fever if severe.
Pointing abscess.

Treatment:

Incision and drainage.
Break loculations.
Send pus for culture if severe/recurrent/immunocompromised.
Antibiotics only if cellulitis, systemic signs, immunosuppression, diabetes, prosthesis, difficult site, recurrent abscess, or incomplete drainage.

IDSA recommends incision and drainage as the treatment for abscesses, carbuncles, and large furuncles; antibiotics are added depending on systemic features such as fever, tachycardia, tachypnoea, abnormal WBC count, impaired host defences, failed initial therapy, or severe disease. (Infectious Diseases Society of America)

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11. Cellulitis

Diffuse infection of skin/subcutaneous tissue.

Usually:

Streptococcus pyogenes.
Staphylococcus aureus.

Features:

Erythema, warmth, swelling, pain.
Poorly demarcated margins.
Fever if severe.

Treatment:

Elevation.
Analgesia.
Anti-streptococcal/anti-staphylococcal antibiotics.
Look for abscess; if abscess present, drain.

Exam trap:

Cellulitis without pus usually needs streptococcal cover.
Purulent infection raises suspicion of Staphylococcus aureus/MRSA depending on setting.

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12. Necrotizing fasciitis

This is an exam favourite.

Red flags

Pain out of proportion.
Rapid progression.
Severe systemic toxicity.
Skin discoloration.
Bullae.
Crepitus.
Anaesthesia of skin.
Dusky necrosis.
Shock.
High lactate.
Failure to respond to simple antibiotics.

Types

Type 1: polymicrobial, diabetics, perineum, abdomen.
Type 2: Group A Streptococcus ± Staph aureus.
Clostridial myonecrosis: gas gangrene.

Management

Do not wait for imaging if clinically obvious.

Immediate resuscitation.
Broad-spectrum IV antibiotics.
Urgent radical surgical debridement.
Repeat debridement every 24–48 hours if needed.
ICU support.

Antibiotic idea:

Broad Gram-positive + Gram-negative + anaerobic cover.
Add MRSA cover if risk/severe hospital infection.
Add clindamycin for toxin suppression when Group A Strep or clostridial disease suspected.

Example conceptual regimen:

Piperacillin-tazobactam or meropenem

• vancomycin/linezolid if MRSA risk

• clindamycin for toxin suppression.

Exam line:
Necrotizing fasciitis is a surgical emergency. Delay in debridement kills.

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13. Fournier gangrene

Necrotizing fasciitis of perineum/genital region.

Risk factors:

Diabetes.
Alcohol misuse.
Immunosuppression.
Perianal sepsis.
Urethral source.
Trauma.

Management:

Resuscitation.
Broad-spectrum antibiotics.
Urgent radical debridement.
Repeat debridement.
Urinary/faecal diversion if needed.
ICU care.

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14. Intra-abdominal sepsis

Common causes:

Appendicitis.
Perforated peptic ulcer.
Perforated diverticulitis.
Bowel ischemia/perforation.
Anastomotic leak.
Pancreatic infection.
Biliary sepsis.
Intra-abdominal abscess.

Organisms:

Gram-negative rods.
Anaerobes.
Enterococcus in selected high-risk cases.
Candida in selected high-risk postoperative/ICU cases.

Management:

Resuscitate.
Broad-spectrum antibiotics covering Gram-negatives and anaerobes.
CT abdomen if stable and diagnosis unclear.
Urgent operation/drainage if unstable or generalized peritonitis.
Percutaneous drainage for suitable localized abscess.
Surgical repair/resection/diversion if leak or perforation.

Antibiotic concept:

Community mild-moderate:

Cephalosporin + metronidazole, or beta-lactam/beta-lactamase inhibitor.

Severe/hospital-acquired/ICU:

Piperacillin-tazobactam or carbapenem depending local resistance and ESBL risk.

Add antifungal only if high-risk: recurrent GI perforation, upper GI leak, prolonged ICU, TPN, immunosuppression, known Candida.

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15. Cholangitis

Classic:

Charcot triad:

Fever, jaundice, right upper quadrant pain.

Reynolds pentad:

Charcot triad + hypotension + confusion.

Management:

Resuscitation.
Blood cultures.
Broad-spectrum antibiotics.
Urgent biliary drainage if severe or not improving — usually ERCP.

Exam line:
Obstructed infected bile duct needs drainage. Antibiotics alone may fail.

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16. Diabetic foot infection

Important because infection severity may be underestimated.

Assess:

Perfusion.
Neuropathy.
Depth.
Probe-to-bone test.
Necrosis/gangrene.
Abscess.
Osteomyelitis.
Systemic sepsis.

Management:

Glycaemic control.
Debridement.
Drain abscess.
Offloading.
Vascular assessment/revascularisation if ischemic.
Antibiotics according to severity.
Osteomyelitis needs prolonged therapy and sometimes bone resection.

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17. Surgical antibiotic pharmacology

Beta-lactams

Penicillins, cephalosporins, carbapenems.

Mechanism:

Inhibit bacterial cell wall synthesis.

Killing:

Time-dependent.

Exam meaning:

Time above MIC matters. In severe sepsis, prolonged infusion beta-lactams may be useful.

Adverse effects:

Allergy, rash, anaphylaxis, C. difficile, renal adjustment for many drugs.

Aminoglycosides

Gentamicin, amikacin.

Mechanism:

Inhibit protein synthesis, 30S ribosome.

Killing:

Concentration-dependent.

Use:

Severe Gram-negative infection, synergy.

Toxicity:

Nephrotoxicity, ototoxicity.

Exam trap:

Dose carefully in renal impairment.

Metronidazole

Covers anaerobes.

Use:

Colorectal surgery, intra-abdominal sepsis, pelvic sepsis, anaerobic soft tissue infection.

Does not cover aerobes.

Vancomycin

Covers Gram-positive organisms including MRSA.

Use:

MRSA risk, resistant Gram-positive infection, prosthetic/device infections.

Toxicity:

Nephrotoxicity, infusion reaction.

Exam trap:

Vancomycin alone does not cover Gram-negatives.

Clindamycin

Covers Gram-positives and anaerobes depending resistance.

Special role:

Suppresses toxin production in Group A Streptococcus and clostridial infection.

Toxicity:

C. difficile risk.

Fluoroquinolones

Gram-negative coverage, some atypical coverage.

Toxicity:

Tendon injury, QT prolongation, dysglycaemia, C. difficile, resistance selection.

Not first choice if safer alternatives exist.

Linezolid

Covers MRSA and VRE.

Toxicity:

Thrombocytopenia, serotonin syndrome risk, neuropathy with prolonged use.

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18. Empiric antibiotic selection: exam approach

Do not memorise random drug lists. Think by source.

Skin/soft tissue, non-purulent

Cover streptococci ± MSSA.

Purulent skin infection

Drain first.
Cover Staph aureus if systemic/severe.
MRSA cover if risk.

Intra-abdominal infection

Cover Gram-negative rods + anaerobes.

Biliary infection

Cover Gram-negative rods.
Add anaerobic cover if severe, bilioenteric anastomosis, or complicated disease.

Hospital-acquired postoperative sepsis

Cover resistant Gram-negatives ± MRSA depending risk.
Think Pseudomonas, ESBL, MRSA, Enterococcus, Candida in selected patients.

Line infection

Blood cultures.
Remove line if septic shock, S. aureus, Candida, persistent bacteraemia, tunnel infection, or metastatic infection.

Prosthetic infection

Biofilm problem.
May need removal or staged revision.
Antibiotics alone often fail.

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19. Antibiotic stewardship

This is increasingly asked.

Correct practice:

Start broad only when necessary.
Take cultures first when safe.
Do not delay antibiotics in septic shock.
Review at 24–48 hours.
Narrow according to culture.
Stop if no infection.
Use shortest effective duration.
Adjust to renal/hepatic function.
Avoid duplicate anaerobic cover.
Avoid unnecessary vancomycin/carbapenem.
Convert IV to oral when improving.

Exam phrase:
“Start smart, then focus.”

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20. Antibiotic duration: high-yield principles

Simple cellulitis:

Usually short course if improving.

Abscess:

Drainage may be enough if no systemic features.

Intra-abdominal infection with adequate source control:

Often around 4 days.

Persistent fever after source control:

Do not simply extend antibiotics. Look for missed collection, leak, necrosis, line infection, pneumonia, DVT/PE, drug fever, C. difficile.

Prophylaxis:

Single dose or less than 24 hours.

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21. Postoperative fever and infection

Approach:

Early: first 48 hours

Inflammatory response.
Atelectasis is often over-blamed.
Transfusion reaction.
Drug fever.
Pneumonia/aspiration.
Severe early wound infection if pain out of proportion.

Day 3–5

Pneumonia.
UTI.
Line infection.
Early intra-abdominal collection.
Anastomotic leak.

Day 5–7 and later

Wound infection.
Deep abscess.
Anastomotic leak.
C. difficile.
DVT/PE.
Infected hematoma.

Exam line:
Tachycardia after colorectal surgery may be the earliest sign of an anastomotic leak.

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22. Management of infected surgical wound

If superficial cellulitis only:

Antibiotics covering likely organisms.
Mark erythema.
Review response.

If pus/discharge:

Open part of wound.
Drain pus.
Send culture.
Irrigate if needed for cleaning, not as SSI prevention.
Dress wound.
Antibiotics if cellulitis/systemic/deep/prosthetic/high-risk.

If fascial dehiscence or deep infection:

Senior help.
Imaging if stable.
Theatre if unstable, fascial breakdown, necrosis, organ-space sepsis.

NICE advises antibiotics for suspected SSI with cellulitis, choosing coverage based on likely organisms, local resistance, and microbiology results. (NICE)

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23. Important special infections

Gas gangrene / clostridial myonecrosis

Severe pain.
Swelling.
Crepitus.
Bronze skin.
Thin brown discharge.
Severe toxicity.
Hemolysis, shock.

Treatment:

Urgent radical debridement or amputation if needed.
High-dose penicillin + clindamycin conceptually.
Broad cover until diagnosis clear.
ICU support.

Tetanus-prone wound

Risk:

Dirty wound, devitalised tissue, puncture wound, soil/manure contamination, burns, crush injury.

Management:

Wound cleaning/debridement.
Check immunisation.
Tetanus toxoid ± human tetanus immunoglobulin depending immunisation status and wound risk.

Human bite

Organisms:

Staph, Strep, anaerobes, Eikenella.

Treatment:

Irrigation.
Debridement.
Avoid primary closure if high-risk.
Co-amoxiclav conceptually.
Hand bites need careful surgical assessment.

Dog/cat bite

Pasteurella, Staph, Strep, anaerobes.

Cat bites puncture deep and infect easily.

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24. Biofilm and foreign body infection

Biofilm forms on:

Prosthetic joints.
Vascular grafts.
Mesh.
Sutures.
Cardiac devices.
Central lines.

Biofilm bacteria are protected from host immunity and antibiotics.

Clinical implications:

Cultures may be difficult.
Long treatment may be needed.
Device removal may be required.
Suppressive antibiotics may be used if device cannot be removed.

Exam line:
Antibiotics cannot reliably sterilise infected prosthetic material.

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25. Common exam traps

Trap 1

“Give antibiotics for abscess.”

Correct answer: Drain the abscess. Antibiotics are adjunctive only in selected cases.

Trap 2

“Continue prophylaxis until drain removed.”

Wrong. Drains are not an indication to continue prophylactic antibiotics.

Trap 3

“Clean surgery always needs antibiotics.”

Wrong. Clean non-prosthetic uncomplicated surgery usually does not need routine prophylaxis.

Trap 4

“Dirty wound needs prophylaxis.”

Wrong. Dirty wound needs treatment-dose antibiotics plus source control.

Trap 5

“Persistent fever means longer antibiotics.”

Wrong. Persistent fever means look for missed source.

Trap 6

“Vancomycin is the strongest surgical prophylaxis.”

Wrong. Vancomycin covers Gram-positives only and is not routine. It misses Gram-negatives.

Trap 7

“Necrotizing fasciitis needs CT confirmation.”

Wrong. If clinically suspected with toxicity, urgent theatre should not wait for imaging.

Trap 8

“Culture swab from wound surface is enough.”

Wrong. Tissue/pus/deep sample is better than superficial swab.

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26. OSCE/viva answer framework

When asked: “How will you manage this patient with suspected surgical infection?”

Say:

“I will assess the patient using ABCDE and look for sepsis or shock. I will give oxygen if needed, establish IV access, send bloods including FBC, CRP, renal function, LFT, clotting, lactate, and take blood cultures before antibiotics if this does not delay treatment. I will identify the source clinically and with imaging if the patient is stable. I will start empiric broad-spectrum antibiotics according to the likely source and local guideline, then arrange urgent source control such as drainage, debridement, removal of infected device, or surgery. I will monitor response, review cultures at 24–48 hours, de-escalate antibiotics, and decide duration based on source control and clinical progress.”

That answer scores.

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27. Memory frameworks

For treating surgical infection: DRAIN

D — Drain pus
R — Remove dead tissue/foreign body
A — Antibiotics appropriate to source
I — Improve perfusion/oxygenation/nutrition
N — Never forget reassessment

For prophylaxis: CLASS

C — Class of wound
L — Likely organisms
A — Antibiotic allergy/local resistance
S — Start before incision
S — Stop early, usually single dose/<24h

For antibiotic stewardship: 4D

Drug — correct spectrum
Dose — correct dose/renal adjustment
De-escalate — narrow after culture
Duration — shortest effective course

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28. Rapid exam questions

1. Best treatment for simple abscess?
Incision and drainage.

2. Clean hernia repair without mesh: routine prophylaxis?
Usually no.

3. Clean hernia repair with mesh: prophylaxis?
Yes.

4. Colorectal surgery prophylaxis should cover what?
Gram-negative rods and anaerobes.

5. Timing of prophylaxis?
Within 60 minutes before incision for most antibiotics.

6. Vancomycin timing?
Begin within 120 minutes before incision.

7. When to redose prophylaxis?
Long operation beyond two half-lives or major blood loss.

8. Duration of prophylaxis?
Single dose or less than 24 hours in most cases.

9. Dirty wound needs what?
Treatment-dose antibiotics plus source control.

10. Necrotizing fasciitis key symptom?
Pain out of proportion.

11. Necrotizing fasciitis management?
Urgent debridement + broad antibiotics + resuscitation.

12. Persistent fever after source control?
Look for missed source, leak, abscess, line infection, C. difficile.

13. Cholangitis definitive management?
Antibiotics plus biliary drainage if severe/not improving.

14. Why do prosthetic infections persist?
Biofilm.

15. Most important principle in surgical sepsis?
Source control.

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Final exam summary

For your exam, think like this:

Prophylaxis prevents predictable contamination.
Treatment manages established infection.
Pus must be drained.
Necrosis must be debrided.
Leaks must be controlled.
Obstruction must be relieved.
Foreign bodies may need removal.
Antibiotics must be early in sepsis, appropriate to source, reviewed daily, narrowed quickly, and stopped as soon as safely possible.