Overview
Definition:
Antibiotic prophylaxis in surgery refers to the administration of antimicrobial agents before a surgical procedure to prevent the development of surgical site infections (SSIs)
It is a critical component of perioperative care, aimed at reducing morbidity, mortality, and healthcare costs associated with SSIs.
Epidemiology:
SSIs are a common type of healthcare-associated infection, contributing significantly to patient morbidity and hospital stay
Prophylactic antibiotics can reduce SSI rates by 15-50% in various surgical procedures, depending on the risk classification and adherence to guidelines.
Clinical Significance:
Effective antibiotic prophylaxis is paramount in preventing SSIs, which can range from superficial skin infections to deep incisional or organ space infections
SSIs can lead to delayed wound healing, prolonged hospitalization, reoperation, sepsis, and increased mortality
Proper prophylaxis is a cornerstone of patient safety and a key metric for surgical quality.
Classification Of Procedures
Clean Procedures:
Procedures performed on uninfected tissue, without entering the respiratory, alimentary, or genitourinary tracts
Typically involve no inflammation and no break in aseptic technique
Examples: Thyroidectomy, inguinal hernia repair (uncomplicated).
Clean Contaminated Procedures:
Procedures where the respiratory, alimentary, or genitourinary tracts are entered under controlled conditions and without unusual contamination
Examples: Cholecystectomy, appendectomy (uncomplicated), hysterectomy.
Contaminated Procedures:
Open, fresh, accidental wounds
operative procedures with major breaks in sterile technique or gross spillage from the gastrointestinal tract
and incisions in which acute, non-purulent inflammation is encountered
Examples: Bowel resection with spillage, drainage of abscess, certain trauma surgeries.
Dirty Procedures:
Old traumatic wounds with retained devitalized tissue and those that involve existing clinical infection or perforated viscera
Examples: Perforated appendix, ruptured viscus, debridement of infected wounds.
Antibiotic Selection And Timing
Selection Criteria:
Antibiotic choice depends on the likely pathogens for the specific procedure, local resistance patterns, patient allergies, and cost
Broad-spectrum coverage is often initiated, narrowing as appropriate postoperatively if cultures are obtained.
Timing Of Administration:
The first dose should be administered within 60 minutes before skin incision
If a long-acting agent is used, it can be given up to 120 minutes before incision
For procedures longer than 4 hours or those involving significant blood loss (>1500 mL), intraoperative redosing may be necessary.
Duration Of Prophylaxis:
Generally, prophylaxis should be limited to 24 hours postoperatively
Continuation beyond this period has not been shown to reduce SSI rates and may contribute to antibiotic resistance and adverse effects
Exception: Certain procedures like cardiac surgery may warrant slightly longer duration based on specific protocols.
Common Agents By Class:
Clean/Clean-Contaminated: First-generation cephalosporins (e.g., Cefazolin) are standard
Alternative for penicillin allergy: Clindamycin or Vancomycin (if MRSA risk)
Contaminated/Dirty: Broad-spectrum agents covering Gram-positives, Gram-negatives, and anaerobes are essential, often combination therapy (e.g., Piperacillin-Tazobactam, Carbapenems).
Procedure Specific Prophylaxis
Gastrointestinal Surgery:
Bowel resection: Cover Gram-positives, Gram-negatives, and anaerobes (e.g., Cefazolin plus Metronidazole, or Piperacillin-Tazobactam)
Appendectomy: Cefazolin or Cefotetan
Cholecystectomy: Cefazolin
Bariatric surgery: Cefazolin plus Clindamycin.
Cardiac And Thoracic Surgery:
Cardiac: Cefazolin
Thoracic (non-cardiac): Cefazolin
Coverage for potential Gram-negative pathogens may be considered in specific high-risk cases.
Orthopedic Surgery:
Prosthetic joint replacement: Cefazolin
Cephalothin or Vancomycin for penicillin-allergic patients with MRSA risk
Spine surgery: Cefazolin.
Gynecologic And Obstetric Surgery:
Cesarean section: Cefazolin
Hysterectomy: Cefazolin plus Metronidazole.
Urologic Surgery:
Procedures involving the urinary tract: Trimethoprim-sulfamethoxazole or a fluoroquinolone if local resistance is low
If urinary tract infection is present, it must be treated before surgery.
Neurosurgery:
Craniotomy: Cefazolin
Spine surgery (non-fusion): Cefazolin.
Challenges And Considerations
Antibiotic Stewardship:
Judicious use of antibiotics to prevent resistance is crucial
Regular review of local antibiograms and adherence to guidelines are essential components of antibiotic stewardship programs.
Patient Allergies:
Penicillin allergy is common
For patients with mild, non-anaphylactic reactions, cephalosporins may be used cautiously
For severe allergies, alternative agents like Clindamycin or Vancomycin are necessary, considering potential MRSA.
Multidrug Resistant Organisms:
Increasing prevalence of MRSA, VRE, and ESBL-producing bacteria necessitates careful selection of prophylactic agents, especially in patients with risk factors or in institutions with high rates of these organisms.
Emerging Guidelines:
Guidelines are periodically updated by organizations like the CDC, SIS (Surgical Infection Society), and WHO
Staying current with the latest evidence-based recommendations is vital for optimal practice.
Key Points
Exam Focus:
Know the classification of surgical procedures and the corresponding recommended prophylactic antibiotics
Understand the timing and duration of prophylaxis
Be aware of alternatives for penicillin-allergic patients.
Clinical Pearls:
Always check local antibiograms for appropriate drug selection
Administer the first dose within 60 minutes of incision
Limit prophylaxis to 24 hours postoperatively unless specific indications exist
Document antibiotic choice, dose, and timing.
Common Mistakes:
Delaying the first dose of antibiotic
Using antibiotics for too long postoperatively
Inadequate coverage for Gram-negative or anaerobic bacteria in contaminated/dirty procedures
Not considering patient allergies or local resistance patterns.