Perioperative antibiotic prophylaxis in the gastric bypass patient: do we achieve therapeutic levels?

Surgery. 2004 Oct;136(4):738-47. doi: 10.1016/j.surg.2004.06.022.


Background: Perioperative surgical antibiotic prophylaxis requires that therapeutically effective drug concentrations be present in the tissues.

Methods: Patients undergoing Roux-en-Y gastric bypass for morbid obesity were given 2 g cefazolin preoperatively, followed by a second dose at 3 hours. Thirty-eight patients were each assigned to 1 of 3 body mass index (BMI) groups: (A) BMI=40-49 (N = 17); (B) BMI=50-59 (N=11); (C) BMI > or= 60 (N=10). Multiple timed serum (baseline; incision, 15, 30, 60 minutes; prior to second prophylactic dose; and closure) and tissue (skin, subcutaneous fat, and omentum) specimens were collected and cefazolin concentration analyzed by microbiological assay.

Results: No significant difference was observed in intraoperative fluid replacement or blood loss among BMI groups. Serum antimicrobial concentrations exceeded resistance breakpoint (32 microg/mL) in 73%, 68%, and 52% of BMI groups A, B, and C, respectively. No significant difference in cefazolin concentration was observed in mean incisional skin and closure tissue specimens in groups A, B, and C. A significant decrease in cefazolin concentration was noted in closure adipose (p=.04), initial (p=.03) and closure omentum (p=.05) tissues in groups B and C compared with A. Over 90% of serum samples exhibited therapeutic concentrations covering 53.8% of gram-positive and 78.6% of gram-negative surgical pathogens. However, therapeutic tissue levels were achieved in only 48.1%, 28.6%, and 10.2% of groups A, B, and C, respectively.

Conclusions: Pharmacokinetic analysis suggests that present dosing strategies may fail to provide adequate perioperative prophylaxis in gastric bypass patients.

MeSH terms

  • Adult
  • Anastomosis, Roux-en-Y
  • Anti-Bacterial Agents / pharmacokinetics
  • Anti-Bacterial Agents / therapeutic use*
  • Antibiotic Prophylaxis*
  • Cefazolin / pharmacokinetics
  • Cefazolin / therapeutic use*
  • Drug Monitoring / methods
  • Female
  • Gastric Bypass / methods*
  • Humans
  • Male
  • Middle Aged
  • Omentum / metabolism
  • Perioperative Care
  • Skin / metabolism
  • Subcutaneous Tissue / metabolism


  • Anti-Bacterial Agents
  • Cefazolin