Reviewed by: Jose Lucar, MD, The George Washington University
Many hospital-based antimicrobial stewardship programs are weighing the adoption of molecular assays for pneumonia. A recent study reports one center’s experience integrating implementation with stewardship.1
It is well known that demonstrating the microbiological etiology of pneumonia is difficult, and as such, better diagnostic tools are needed for that purpose. Paired with traditional diagnostic methods and clinical judgment, rapid molecular assays that detect multiple respiratory pathogens (including a broad range of bacteria and viruses) from a lower respiratory tract sample are playing an increasing role in the microbiological diagnosis of acute respiratory tract infections. Previously, small retrospective studies have evaluated the potential antimicrobial stewardship impact of the BioFire Pneumonia Panel, a commercial multiplex PCR assay2,3. However, it remains unclear whether its use effectively changes patient outcomes, i.e., a decrease in time to optimal therapy or the ultimate treatment duration, in hospitalized patients with pneumonia.
Miller and colleagues reported findings of a single-center, retrospective, pre- and post-intervention analysis that evaluated the impact of the BioFire Pneumonia Panel (PNP) in adult ICU patients. The pre-PNP cohort (May-August 2019) included 66 patients with respiratory culture results, while the post-PNP implementation cohort (May-August 2020) included 58 patients with PNP with paired respiratory culture results. The institution’s pneumonia treatment guidelines recommended PNP use in all patients with HAP and VAP, as well as some patients with CAP (if severe, receiving broad-spectrum agents, or not improving), and the results were subject of prospective audit and feedback by their ASP. Exclusion criteria included having a positive SARS-CoV-2 PCR test, patients not receiving antibiotics, or need for antibiotic therapy beyond a respiratory infection. There were significant differences in patient characteristics between both groups, including sex, type of admitting ICU unit, the type of pneumonia (i.e., CAP was more common in the post-PNP cohort), and the type of specimen source (sputum and endotracheal aspirates were more common in the post-PNP cohort).
Median time to anti-MRSA agent discontinuation, the primary outcome of the study, was 49.1 h in the pre-PNP and 41.8 h in the post-PNP cohort (p = 0.28). Median time to discontinuation of antipseudomonal drugs, a key secondary outcome, was 134.4 h in the pre-PNP and 98.1 h in the post-PNP cohort (p = 0.47). Possible reasons for non-statistically significant numerical trend include the small sample size, confounding from the early months of the COVID-19 pandemic in the post-PNP cohort (known antibiotic overuse), different types of specimens used, minimal clinician education, and limited number of ASP interventions due to pandemic demands. An important limitation of this study is the fact that their institution does not currently utilize the MRSA nares PCR tool, which is known to have a strong negative predictive value and has already been shown to reduce the duration of MRSA therapy in patients with pneumonia. As the authors concluded, further studies are needed to help delineate the impact of multiplex PCR pneumonia panels in optimizing antimicrobial therapy with a particular emphasis in the role of stewardship interventions and clinician education.
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