Antibiotic prophylaxis in bariatric surgery with continuous infusion of cefazolin: determination of concentration in adipose tissue.

Background: The aim of this study was to evaluate the concentration of cefazolin in adipose tissue of patients undergoing bariatric surgery.

Methods: Eighteen patients undergoing bariatric surgery were evaluated during the period from October 2011 to May 2012. All patients had a dosage schedule of antibiotic prophylaxis with cefazolin administered as follows: first, 2 g in anesthetic induction, followed by continuous infusion of 1 g diluted in 250 ml of saline solution. Adipose samples, collected soon after the incision (initial) and before the skin synthesis (final), were analyzed using reverse phase high-pressure liquid chromatography. The level of significance adopted was 5 %.

Results: The cefazolin concentration in the adipose tissue samples at the beginning of surgery was an average of 6.66 ± 2.56 ug/ml. The mean concentration before the skin synthesis was 7.93 ± 2.54 ug/ml. Patients with BMI < 40 kg/m(2) had higher initial and final sample concentrations of cefazolin than patients with BMI ≥ 40 kg/m(2). There was no surgical site infection (SSI) in any of the patients.

Conclusions: In bariatric surgeries, addition of a 1 g increase of cefazolin, administered through continuous intravenous infusion, to the currently recommended dose of 2 g administered in anesthetic induction provided a concentration in the adipose tissue above the minimum inhibitory concentration (MIC) of the main causal agents of SSI. An inverse correlation between BMI and concentration of cefazolin in adipose tissue was observed.