46. Antimicrobial Stewardship’s Selective Antibiotic Suppression Does Not Lead to Adverse Outcomes in Neutropenic Patients with Gram-Negative Bacteremia

Abstract Background An antimicrobial stewardship program (ASP) strategy to minimize the use of overly broad antimicrobials is to suppress specific antimicrobial susceptibility results when isolates are sensitive to narrow antibiotics. There is limited data on possible adverse outcomes of this method. Patients with febrile neutropenia (FN) and gram-negative bacteremia (GNB) whose culture is sensitive to non-pseudomonal antibiotics still require broader pseudomonal coverage to treat the syndrome of FN. We evaluated if ASP suppression of anti-pseudomonal antibiotics adversely affects patients with FN and GNB. Methods In February 2018, our institution’s ASP began suppressing cefepime and meropenem susceptibility results from E. coli, Klebsiella spp, and Proteus spp when sensitive to cefepime (MIC ≤ 2), ceftriaxone and ceftazidime. We performed a retrospective analysis of patients with FN and GNB from 2016 – 2020 to evaluate the appropriateness of antibiotic regimens before and after the ASP intervention. Antibiotic regimens were deemed inappropriate if the patient was de-escalated to a narrow-spectrum, non-pseudomonal agent while neutropenic. Of 338 inpatient encounters identified with any bacteremia and FN, 49 were due to non-Pseudomonas, non-ESBL GNB, 20 before and 29 after the intervention. Sixteen of the 29 post-intervention patients were excluded, as their isolates did not meet suppression criteria. This resulted in a total of 13 patients in the post-intervention group. Results After culture susceptibility reports were released, 3 out of 20 patients in the pre-intervention group (15%) and 4 out of 13 patients in the post-intervention group (30.8%) were inappropriately tailored to narrow-spectrum antibiotics (p=0.39). There was no significant difference in 30-day mortality, 10.0% pre- and 0% post-intervention (p=0.50), or amount of meropenem prescribed, 45% pre- and 38.5% post-intervention (p=0.74). Conclusion These data show no significant difference in inappropriate antibiotic regimens prescribed for patients with FN and GNB after ASP antibiotic suppression was implemented. 30-day mortality was also not affected. The ASP intervention did not decrease meropenem prescriptions in this patient group, which may be appropriate. Larger studies are needed to verify these findings. Disclosures Ryan K. Dare, MD, MS, Accelerate Diagnostics, Inc (Research Grant or Support) Mary Burgess, MD, Pfizer Inc (Grant/Research Support)