Continuous versus intermittent infusion of prophylactic cefoxitin after colorectal surgery: a pilot study.

STUDY OBJECTIVE: To compare 30-day postoperative surgical site infections (SSIs) and rates of antibiotic discontinuation within 24 hours after surgery in patients receiving continuous-infusion versus intermittent-infusion cefoxitin for postoperative antibiotic prophylaxis. DESIGN: Retrospective, cohort-matched pilot study. SETTING: Tertiary-care medical center. PATIENTS: One hundred sixteen adults undergoing colorectal surgery between August 1, 2004, and February 28, 2007. INTERVENTION: Cefoxitin prophylaxis was administered as a continuous infusion in 58 patients and as an intermittent infusion in 58 patients (controls). The controls received weight-based doses of cefoxitin (1 g if < or = 80 kg or 2 g if > 80 kg) every 8 hours for three doses, starting 3 hours after surgery and completed within 24 hours. The continuous-infusion group were given weight-based doses of cefoxitin (3 g if < or = 80 kg, 6 g if > 80 kg), started immediately after surgery and infused over 20 hours. MEASUREMENTS AND MAIN RESULTS: Patients and controls were matched according to colorectal procedure and risk index category. They were stratified by medium risk (50 patients) and low risk (66 patients) for the end point of 30-day postoperative SSI. For the 25 medium-risk patients who received the continuous infusion, a 50% relative reduction in the 30-day postoperative SSI rate was observed with continuous versus intermittent infusion (4% vs 8%, p=0.55). For the 66 low-risk patients, 30-day postoperative SSI rates were equal (3%) with both intermittent and continuous infusions. Risk stratification was not performed for the proportion of patients who discontinued antibiotic prophylaxis within 24 hours after surgery. All patients receiving the continuous infusion met this end point compared with 47 (83.9%) of the 56 controls (p=0.0015) included in the analysis. CONCLUSION: Compared with intermittent infusion, continuous infusion of cefoxitin for postoperative prophylaxis resulted in a nonsignificant reduction in 30-day postoperative SSI rates in medium-risk patients undergoing colorectal surgery. Continuous infusion also resulted in reliable discontinuation of postoperative prophylaxis within 24 hours.

Cefazolin tolerance does not predict ceftriaxone hypersensitivity: unique side chains precipitate anaphylaxis.

A 48-year-old woman with a questionable history of an unspecified ceftriaxone allergy was treated with cefazolin for surgical antibiotic prophylaxis. After she tolerated cefazolin therapy for 4 days, the medical staff concluded that her allergy history was inaccurate, and she was treated with intravenous ceftriaxone for suspected nosocomial pneumonia. Approximately 10 minutes after the start of the infusion, the patient experienced anaphylaxis. Initial symptoms of oral angioedema and laryngopharyngeal constriction progressed to dyspnea, tachypnea, hypotension, and tachycardia, all of which quickly resolved after immediate treatment with hydrocortisone, diphenhydramine, and epinephrine. Skin testing with cefazolin, cefepime, and ceftriaxone revealed that the likely allergic determinant mediating the patient's hypersensitivity reaction was the unique ceftriaxone R2 side chain and not the beta-lactam ring, which initially was suspected by the physician. Immunoglobulin E-mediated hypersensitivity reactions to cephalosporins may occur due to antibody complexes with the beta-lactam ring or various cephalosporin side chains. Misconceptions regarding the nature of cephalosporin allergies complicate antibiotic selection for patients with questionable allergy histories and may lead to inappropriate drug reexposure and anaphylaxis. Detailed understanding of the antigenic determinants that mediate hypersensitivity reactions is essential for clinicians to avoid type 1 reactions in patients with a suspected allergy to cephalosporins.