Comparison of β-Lactam vs Non–β-Lactam Prophylaxis in Elective Colorectal Surgery

Overview

This multicenter retrospective cohort study evaluated 30-day surgical site infection (SSI) rates in elective colorectal surgery patients receiving β-lactam versus non–β-lactam antibiotic prophylaxis, controlling for guideline-concordant dosing and timing. Findings indicate that β-lactam prophylaxis is associated with lower SSI rates compared to non–β-lactam alternatives.

Background

Surgical site infections (SSIs) significantly increase patient morbidity and healthcare costs, particularly in colorectal surgery which carries a high SSI risk. β-Lactam antibiotics are preferred for surgical prophylaxis due to their spectrum, pharmacokinetics, safety, and cost. However, patients with penicillin or β-lactam allergies often receive non–β-lactam alternatives, which have been linked to higher SSI rates. Prior studies have not fully controlled for dosing and timing adherence, potentially confounding results.

Data Highlights

The study included adult patients undergoing elective colorectal surgery from 73 Michigan hospitals between 2012 and 2021. Patients received either guideline-concordant β-lactam or non–β-lactam prophylaxis. Exclusions applied for non-elective surgeries, inappropriate dosing/timing, and other factors. Outcomes measured included 30-day SSI and Clostridioides difficile infection (CDI) rates, with adjustments for demographic and clinical covariates.

Key Findings

• β-Lactam prophylaxis regimens included cefazolin plus metronidazole, cefoxitin, cefotetan, ampicillin-sulbactam, ceftriaxone plus metronidazole, and ertapenem.
• Non–β-lactam alternatives included clindamycin plus an aminoglycoside or fluoroquinolone, and metronidazole plus an aminoglycoside or fluoroquinolone.
• Patients receiving β-lactam prophylaxis had significantly lower 30-day SSI rates compared to those receiving non–β-lactam alternatives.
• The study controlled for guideline-concordant antibiotic dosing and timing, minimizing confounding from procedural adherence.
• Race, BMI, diabetes, smoking, corticosteroid use, wound classification, ASA score, surgical approach, and MOABP receipt were included as covariates in analyses.

Clinical Implications

Clinicians should prioritize β-lactam antibiotics for surgical prophylaxis in elective colorectal procedures when no true allergy exists, as these agents are associated with reduced SSI risk. Careful adherence to guideline-concordant dosing and timing remains critical to optimize prophylactic efficacy. Avoiding unnecessary use of non–β-lactam alternatives may improve patient outcomes and reduce healthcare costs.

Conclusion

This study supports the preferential use of β-lactam antibiotics for elective colorectal surgical prophylaxis due to their association with lower SSI rates, even after controlling for dosing and timing adherence. Optimizing antibiotic selection is a key modifiable factor to reduce postoperative infections.

References

1. Michigan Surgical Quality Collaborative (MSQC) Database Studies
2. Surgical Care Improvement Project and ASHP Guidelines