Among patients hospitalized with a bloodstream infection (BSI), administration of a b-lactam agent prior to vancomycin may be associated with a decreased mortality risk, according to findings published in Clinical Infectious Diseases.

Patients (N=3376) aged 13 years and older who were hospitalized with a BSI between 2016 and 2020 were included in this retrospective observational study. In addition, eligible patients included those with a BSI caused by Gram-negative or Gram-positive organisms. The primary outcome was mortality within 7 days from the time of blood culture collection. To balance patient cohorts, the researchers performed a propensity score analysis.

Of patients included in the final analysis, 2685 (79.5%) received a b-lactam agent (79.5%) and 691 (20.5%) received vancomycin as initial antibiotic therapy. The b-lactam agents were piperacillin-tazobactam (47.9%), cefepime (42.0%), and meropenem (5%).


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Among patients in both the b-lactam and vancomycin cohorts, the median ages were 65 and 63 years, 44.5% and 43.3% were women, 11.8% and 11.7% were severely immunocompromised, and 35.6% and 41.4% were transferred to the intensive care unit, respectively.

On analysis of patients’ blood culture specimens, the researchers found that BSIs were most frequently caused by Staphylococcus aureus (22.5%), Escherichia coli (20.8%), and Klebsiella pneumoniae (13.9%); and 11% of patients had polymicrobial infections.

Mortality occurred among 2.8% patients during the first 48 hours after infection, 7.0% within the first 7 days, and 16.8% within the first 30 days. During the first 7 days, mortality rates were most increased among patients with BSIs caused by Acinetobacter baumannii (16.3%), followed by Pseudomonas aeruginosa (12.1%), and Streptococcus pyogenes (12.1%).

Of note, the researchers found an association between 7-day mortality risk and each additional unit increase of both lactate concentrations (adjusted odds ratio [aOR], 1.28; 95% CI, 1.23-1.34; P <.001) and Pitt bacteremia scores (aOR, 1.26; 95% CI, 1.17-1.37; P <.001). In addition, patients who received initial treatment with a Gram-negative agent had a decreased risk of mortality (aOR, 0.48; 95% CI, 0.33-0.69; P <.001).

This study was limited by its retrospective design, in which it remains unclear what the motivations were for the patients to receive initial therapy with 1 antibiotic over another. Further limitations included the lack of data on antibiotics that were administered prior to the first day of blood culture collection.

The researchers concluded that “prioritizing initial β-lactam administration [over vancomycin] has the potential to save 737 lives per year, underscoring the significant impact of a relatively simple practice change.”

Disclosure: One author declared affiliations with industry. Please see the original reference for a full list of disclosures.

Reference

Amoah J, Klein EY, Chiotos K, et al. Administration of a β-lactam prior to vancomycin as the first dose of antibiotic therapy improves survival in patients with bloodstream infections. Clin Infect Dis. 2021;ciab865. doi:10.1093/cid/ciab865