1061. Decreased Utilization of Piperacillin–Tazobactam for Escherichia coli and Klebsiella Bacteremia due to Selective Susceptibility Reporting

Abstract Background Over 2 million people in the United States are diagnosed with antibiotic-resistant infections annually. The Infectious Diseases Society of America (IDSA) recommends cascade reporting of antibiotic susceptibility data by the clinical microbiology laboratory as an intervention to decrease resistance, though this is based on low-quality evidence. Methods We conducted a retrospective study to assess the effect of cascade susceptibility reporting on prescribing practices and patient outcomes. A cascaded testing algorithm was executed wherein susceptibility data for piperacillin–tazobactam (PT) was suppressed from the susceptibility report if an organism was susceptible to ceftriaxone. Patients with positive monomicrobial blood cultures with non-ESBL Escherichia coli (E. coli) or Klebsiella isolates in blood cultures and receiving empiric PT were included. Data were collected one year prior and one year after cascading protocol implementation, and included patient demographics, length of stay (LOS), duration of antibiotics, time to de-escalation, and adverse events including acute kidney injury (AKI) and Clostridioides difficile infection (CDI). Results 212 patients (108 pre-intervention and 104 post-intervention) were included. 87% of patients were de-escalated from PT pre-intervention, while 90% were deescalated post-intervention. Mean time to deescalation decreased from 30 hours before to 17 hours after cascade implementation (P = 0.02) (Figure 1). Median LOS decreased from 15 to 10 days following the intervention (P = 0.12). While the rate of AKI increased from 14 to 19% post-intervention (P = 0.89), the rate of CDI (2 vs. 2 patients) was comparable among both cohorts (P = 0.97) (Figure 2). Conclusion While cascade susceptibility reporting is recommended by the IDSA as a tool for antimicrobial stewardship, this recommendation has weak support due to paucity of data. In this study, we found that selective susceptibility reporting has the potential to decrease the use of PT and to reduce LOS in patients with E. coli and Klebsiella bacteremia. Further research to better identify patient populations most impacted by a cascade algorithm and its overall effectiveness as a stewardship tool is needed. Disclosures All authors: No reported disclosures.