Surgical Antimicrobial Prophylaxis

Perioperative antibiotic prophylaxis is:

Epidemiology

Risk factors for SSI:

  • Appropriate antibiotics
  • Infection control
  • Surgical technique
  • Duration of surgery
  • Sterilisation
  • Preparation
  • Temperature
  • BSL
  • Medical conditions

Administration

Key principles:

  • Hospitals should establish a multidisciplinary antimicrobial team who develop, implement, and audit adherence to protocols
  • Drug administration is the responsibility of the anaesthetist
  • Drug should be administered within 60 minutes prior to skin incision, except for vancomycin and fluoroquinolones
  • Single dose is preferred
    Repeat doses are indicated if:
    • Duration of procedure compared to half-life of antibiotic
      Usually re-dose at two half-lives.
    • Significant blood loss
      ⩾1.5L, independent of antibiotic used.
      Dependent on VD; low VD indicates greater amount of antibiotic lost in blood.

Antibiotic Selection

Principles:

  • Regimen needs to be modified based on:
  • Patient factors
    • Presence of infection
    • MRSA risk factors
    • Recent travel
  • System factors
    • Local resistance patterns
  • Avoid broad-spectrum agents
  • Note that penicillin-allergic patients have significantly ↑ rates of C. difficile, VRE, MRSA infections, and longer hospital stays
    Therefore, inappropriate labeling of patients as penicillin-allergic has significant impact on care.

Based on normal flora of region:

  • Skin
    Including cardiac, vascular, neurosurgery.
    • Cefazolin
  • Bowel
    • Non-obstructed
      • Cefazolin
    • Obstructed or appendicitis
      • Cefazolin and metronidazole
  • Orthopaedics
    • General
      • Cefazolin
    • Gustilo Type 3 open fracture (>10cm soft tissue injury)
      • Aminoglycoside
  • Neurosurgery
    • General
      • Cefazolin
    • Penetrating head trauma
      • Cefazolin and aminoglycoside
        Empirically; i.e. without evidence of meningitis.
    • Head trauma with sinus involvement
      • Ceftriaxone
  • Urological
    • With lower tract instrumentation:
      • Cefazolin
      • Fluoroquinolone
    • With hardware implantation:
      • Aminoglycoside
    • Clean-contaminated
      • Cefazolin and metronidazole
  • Liver transplant
    • Piperacillin-tazobactam

Special circumstances:

  • Severe immediate or delayed penicillin hypersensitivity
    Substitution depends on concern about Gram negative infection; cefazolin has better Gram negative coverage than clindamycin and so this is not a like-for-like substitution.
    • If minimal concern
      e.g. Head and neck.
      • Clindamycin alone
        For minor surgery.
      • Clindamycin and vancomycin
        For everything else: neurosurgery, orthopaedics, cardiac
    • If concerned
      e.g. Bowel, biliary, obstetric, gynaecological:
      • Clindamycin and aminoglycoside
      • Aztreonam
      • Fluoroquinolone
  • Hardware
    For high risk patients:
    • Vancomycin and cefazolin
  • Known or suspected MRSA
    • Risk factors:
      • Recent hospitalisation
      • Nursing-home residents
      • Haemodialysis patients
    • Consider vancomycin

Dosing and Timing

  • Patients on regular antibiotics should be re-dosed perioperatively as per the above re-dosing interval
    • If in doubt and the drug has a wide therapeutic range (e.g. β-lactams), it is likely safe to re-dose
  • Skin incision can occur prior to completion of antibiotic infusion, but infusion should be running for at least 15 minutes prior to incision to allow adequate tissue concentration
Drug | Adult Dose | Paediatric Dose | Time prior to skin incision | Re-dosing Interval (with normal renal function) | Re-dosing Dose |

+—————+——————+—————–+——————————————————-+————————————————-+—————-+ | Cephazolin | 2g, 3g if >120kg | 50mg/kg | Ideally 15 minutes, but 1-2 minutes may be equivalent | 4 hours | Full | | Clindamycin | | | Start 15-60 minutes prior to incision | 6 hours | Full | | Ampicillin | 2g | 50mg/kg | 2 hours | Full | | | Vancomycin | 15mg/kg | 15mg/kg | Start 15-120 minutes prior to incision | >8 hours | Half | | Ciprofloxacin | 400mg | 10mg/kg | Within 120 minutes prior to incision | - | - | | Gentamicin | 2.5-5mg/kg | 2.5mg/kg | Within 60 minutes | - | - |

Gentamycin dosing should be based upon the expected duration of cover needed:

  • 2.5mg/kg when <6 hours
  • 5mg/kg when up to 24 hours

Adjuncts

  • Mupriocin nasal ointment
    Reduced SSIs in S. Aureus colonised patients.

Inappropriate Administration

Antibiotic prophylaxis is not recommended in the following circumstances (and may ↑ risk due to development of resistance):

  • After surgery
  • With indwelling drains

Infective Endocarditis Prophylaxis

Infective endocarditis prophylaxis:

  • Was traditionally given in procedures leading to bacteraemia
    Noting that many activities of daily living (e.g. eating) also lead to a bacteraemia.
  • May prevent an exceedingly small number of IE cases
  • Causes greater harm due to antibiotic-associated adverse events

Epidemiology

Patients with the highest risk of an adverse outcome from IE:

  • Valvular disease
  • Valve replacement
  • HOCM
  • Previous IE
  • Structural congenital heart disease
    • Including surgically corrected or palliated conditions
    • Excluding:
      • Isolated ASD
      • Fully repaired VSD
      • Fully repaired PDA
  • Indigenous Australians with rheumatic heart disease

Administration

IE prophylaxis should be given:

  • Only if a patient is at high risk of an adverse outcome
    See above list.
  • Only for:
    • Dental procedures involving:
      • Manipulation of gingival tissue
      • Manipulation of periapical region of teeth
      • Perforation of oral mucosa
    • Respiratory procedures involving mucosal incision
      e.g. Tonsillectomy, adenoidectomy.
    • Procedures involving infected muscle, skin, or tissue

Antibiotic administration:

  • Should cover any known infection at the site of procedure
  • Given pre-procedure
    Up to 2 hours post-procedure if inadvertently missed.
  • Otherwise, the following are reasonable regimens:
    • PO
      Amoxicillin 50mg/kg, up to 2g.
    • IV
      Cephazolin 50mg/kg, up to 1g.
    • β-lactam allergy
      Clindamycin 20mg/kg, up to 600mg.

References

  1. Magiorakos A-P, Europäisches Zentrum für die Prävention und die Kontrolle von Krankheiten, editors. Systematic review and evidence-based guidance on perioperative antibiotic prophylaxis. Stockholm; 2013. 46 p. (ECDC Technical report).
  2. Bratzler DW, Dellinger EP, Olsen KM, Perl TM, Auwaerter PG, Bolon MK, et al. Clinical practice guidelines for antimicrobial prophylaxis in surgery. Am J Health Syst Pharm. 2013 Feb 1;70(3):195–283.
  3. Overview | Prophylaxis against infective endocarditis: antimicrobial prophylaxis against infective endocarditis in adults and children undergoing interventional procedures | Guidance | NICE [Internet]. [cited 2019 Dec 1]. Available from: https://www.nice.org.uk/Guidance/cg64
  4. Wilson Walter, Taubert Kathryn A., Gewitz Michael, Lockhart Peter B., Baddour Larry M., Levison Matthew, et al. Prevention of Infective Endocarditis. Circulation. 2007 Oct 9;116(15):1736–54.
  5. Bersten, A. D., & Handy, J. M. (2018). Oh’s Intensive Care Manual. Elsevier Gezondheidszorg.