248 - Why so Much Vancomycin and Piperacillin/Tazobactam Usage Given Known Risks of Nephrotoxicity

Background: Despite years of published data describing the increased risk of nephrotoxicity with use of vancomycin and piperacillin/tazobactam (VPT), this combination remains one of the most utilized antibiotic combinations at our institution.  There is limited data describing the appropriateness of empiric use of this broad-spectrum regimen.  Our primary objective was to evaluate the appropriateness of the anti-methicillin resistant Staphylococcus aureus (MRSA), anti-pseudomonal, and anti-anaerobic spectrum of activity for patients empirically treated with this combination.  Our secondary objective was to evaluate the appropriateness of diagnostic evaluation in patients started on this combination.

Methods: A retrospective cohort study was performed on a random sample of unique patients prescribed the combination of VPT from October 2019 through March 2020.  Demographic and clinical data were abstracted from the electronic medical record.  Based on predetermined criteria, we evaluated the appropriateness of the spectrum of activity of empiric therapy and the diagnostic evaluation.

Results: Of 100 patients evaluated, 96 patients (96%) received VPT as empiric treatment. The indications for use are shown in Table 1.  Pneumonia and soft tissue/bone/joint infections were the most common indications.  The appropriateness of anti-MRSA, anti-pseudomonal, and anti-anaerobic therapy is shown in Table 2.  In only 35% of patients was the full spectrum of activity appropriate. Of 47 patients treated empirically for pneumonia, 35 (74%) had an order for a respiratory culture and 7 (15%) for a nasal MRSA surveillance culture.  Of 30 patients treated empirically for soft tissue//joint infections, wound cultures were obtained in 22 (73%).  Nineteen patients underwent surgical intervention, of whom 17 (89%) had cultures obtained. Table 1. Indications for Empiric Vancomycin and Piperacillin/tazobactam Combination Therapy
Table 2: Appropriateness of Spectrum of Activity for Empiric Vancomycin and Piperacillin/tazobactam Combination Therapy


Conclusion: At our institution VPT use was usually empiric and unnecessarily broad for the syndrome being treated.  Microbiologic testing was suboptimal and may have resulted in prolonged therapy.  Although interventions aimed at de-escalating VPT are useful, interventions aimed at ensuring appropriate empiric use of this combination and ensuring appropriate diagnostic testing may be just as important.