2019A13 Outline the principles of antibiotic prophylaxis for surgical site infections using
cefazolin in knee joint replacement surgery as an example.

Aim

Cefazolin for joint replacement surgery

Indicated

(i.e. not in all surgery at clean sites)

·   Moderate risk

·   Severe morbidity

·   Use of implant

Bactericidal preferably

·   Yes

Penetrates the relevant tissues

·   Good for skin, bone, joint

Targets the relevant microbes

·   First generation cephalosporins effective against skin commensal gram positive cocci

·   (Note gram negative rods common in hospitalized patients)

Low risk of encountering antimicrobial resistance

·   Low risk if from community

·   But ineffective against MRSA, use vancomycin instead if in hospital several days

Low risk of promoting microbial resistance

·   Minimal necessary duration: 24 hours total

·   Minimal necessary spectrum: i.e. not piperacillin/tazobactam

Consideration

Cefazolin for joint replacement surgery

Dose

·   25mg/kg pre-induction

Route

·   IV ideal

Rapid onset

·   Ideally 30-60 mins pre-incision, to allow penetration of skin

·   MUST be well before tourniquet if knee replacement

Long duration: ensure cover during long procedure

·   Repeat at 4 hours if surgery ongoing

·   Repeat at 8 hours post-op

Adjustment in organ dysfunction

·   Cefazolin is renally cleared. ↓ frequency if CrCl reduced esp <30mL/min

Side effects

·   High therapeutic index

·   Risk of anaphylaxis

Cost

·   Cheap