A single-institution retrospective analysis on the administration of β-lactam antibiotics prior to vancomycin in bacteremic patients.

Background: The 2021 Surviving Sepsis Guidelines emphasize prompt antibiotic administration as a recommendation for septic patients. Instead of focusing solely on timing, we aimed to investigate whether the sequence of antibiotic administration influences mortality.

Methods: This single-institution retrospective study included patients over 18 years old with confirmed bacteremia between January 1, 2021, and July 1, 2023, who received sequential antibiotic administration of intravenous β-lactam and vancomycin within the first 6 hours of admission. Our primary objective was to determine the odds ratio for 30-day mortality based upon antibiotic class administered first.

Results: Of 6143 patients generated from an electronic search, 222 patients were included in the β-lactam-first group, and 16 were included in the vancomycin-first group. The most common β-lactam antibiotic administered was piperacillin-tazobactam (58.40%) followed by cefepime (25.47%) and then ceftriaxone (13.03%). For patients with monomicrobial bacteremia, the most common bacterial infections included Escherichia coli (25.21%), methicillin-resistant Staphylococcus aureus (13.45%), methicillin-susceptible S. aureus (11.34%), and Proteus mirabilis (7.56%). The calculated odds ratio for 30-day mortality was 0.40 (95% confidence interval 0.089-1.831), indicating a decreased occurrence of mortality within 30 days for patients who received β-lactam antibiotics first, although this result was not statistically significant due to limited sample size, particularly within the vancomycin-first group.

Conclusion: Although not statistically significant, the prompt administration of β-lactam antibiotics before vancomycin may confer a mortality benefit in patients with bacteremia. Further studies are needed to validate this finding.