88. Effect of an MDR Enterobacterales Screening Tool on Antibiotic Prescribing for Abdominal Infections Caused by Mixed Bacteria

Abstract

Abstract Background Background: Choosing antibiotics for infections caused by mixed Enterobacterales is challenging. Our microbiology lab implemented a multi-drug resistance (MDR) screen for cultures with mixed gram-negative to direct clinicians to use 3rd generation cephalosporins for screen neg. pathogens, and to use broader beta-lactams for screen-pos. pathogens. Here we report the effect of MDR screen on final antibiotic choice. Methods Methods: We retrospectively reviewed cases with abdominal infections caused by mixed bacteria at UNC Medical Center between August and November 2020. Cultures with non-Enterobacteraeles gram negatives were excluded. MDR screen was done by plating mixed Enterobacterales on HardyCHROM™ ESBL agar. Screen-pos. cases were updated “MDR Enterobacterales present” and pathogens were identified with full susceptibilities. Screen-neg. cases were labeled “MDR Enterobacterales not present”. Definitely covering antibiotics were defined by the use of 3rd generation cephalosporins for screen neg. cases, or based on susceptibilities in case of screen pos. organisms or concomitant bacteremia. Possibly covering antibiotics included regimens whose susceptibility could not be predicted based on the screen (e.g., amox/clav or quinolone+metronidazole). Results Results: 51 cases were identified. Median age was 51 years (range 10 to 87). 54.9% were female and 45.1% male. Infections included intra-abdominal abscesses (n =35), perirectal or scrotal abscesses (10), abdominal wound infections (4), perineal necrotizing fasciitis (1), and cholecystitis (1). Sample types were abscess fluid (43), wound purulence (4) or tissue (3). MDR screen was pos. in 7.8%. Antibiotics were adjusted in 17.6% as a result of the screen report. 31.5% of final antibiotics definitely covered the isolated bacteria, 56.9% possibly covered, and 5.9% did not have an active antibiotic. Among screen pos. cases, final antibiotics definitely covered in 75% and possibly in 25%. Conclusion Conclusions: The MDR Enterobacterales screening tool for abdominal infections had limited impact on final antibiotic choice, but was useful when positive. Further directions include assessment of provider understanding of the MDR screen results and investigation of utility of screen in other infection types. Disclosures All Authors: No reported disclosures