Incidence of surgical infection in cefazolin 3 g versus 2 g for colorectal surgery in obese patients.

Objective: To compare the incidence of surgical site infection (SSI) between cefazolin 3 g and 2 g surgical prophylaxis in patients weighing ≥120 kg that undergo elective colorectal surgery.

Methods: A multicenter, retrospective cohort study was performed utilizing a validated database of elective colorectal surgeries in Michigan acute care hospitals. Adults weighing ≥120 kg who received cefazolin and metronidazole for surgical prophylaxis between 7/2012 and 6/2021 were included. The primary outcome was SSI, which was defined as an infection diagnosed within 30 days following the principal operative procedure. Multivariable logistic regression was used to identify variables associated with SSI; the exposure of interest was cefazolin 3 g surgical prophylaxis.

Results: A total of 581 patients were included; of these, 367 (63.1%) received cefazolin 3 g, while 214 (36.8%) received 2 g. Patients who received cefazolin 3 g had less optimal antibiotic timing (324 [88.3%] vs 200 [93.5%]; P = .043) and a higher receipt of at least 1 of the prophylaxis antibiotics after incision (22 [6%] vs 5 [2.3%]; P = .043). There was no SSI difference between cefazolin 3 g and 2 g cohorts (23 [6.3%] vs 16 [7.5%], P = .574). When accounting for age, smoking status, and surgical duration, cefazolin 3 g was not associated with a reduction in SSI (adjOR, .64; 95%CI, .32-1.29).

Conclusions: Surgical prophylaxis with cefazolin 3 g, in combination with metronidazole, was not associated with decreased SSI compared to 2 g dosing in obese patients undergoing elective colorectal surgery.