1099. The Correlation Between Antimicrobial Utilization and Resistance in a Medical Intensive Care Unit

BACKGROUND: The relationship between antimicrobial utilization and the incidence of antimicrobial-resistant pathogens can be obscured by a lack of longitudinal data. We used 9 years of antimicrobial utilization data combined with a unique metric of antimicrobial resistance to examine this relationship. METHODS: The medical intensive care unit (MICU) at UVMMC has 22 beds. The unit’s size and location did not change during the study. Since 2010, defined daily doses (DDD) in the MICU for ceftazidime, ceftriaxone, cefepime, ciprofloxacin, levofloxacin, piperacillin–tazobactam, meropenem, and vancomycin were measured. Concurrently, a database of positive cultures acquired in MICU, whether colonization or infection, was built for 6 selected organisms: Clostridioides difficile, methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, ceftazidime-resistant Gram-negative bacilli, fluoroquinolone-resistant Pseudomonas aeruginosa (QRPA), and Stenotrophomonas maltophilia. The occurrence of these 6 organisms/1,000 patient-days is termed “resistance index.” Data for both metrics were collected in the same way, by the same person, throughout. The relationship between these 2 measures was analyzed with simple linear regression. RESULTS: From 2010 to 2018, the use of 8 broad-spectrum antibiotics fell in a linear fashion from 12.11 to 4.39 DDD/100,000 patient-days. The resistance index for the 6 multidrug-resistant organisms in MICU also fell in parallel from 6.5 to 1.5/1,000 patient-days (figure, r = 0.9, P = 0.001). For the 2 quinolones specifically, use fell from 2.26 to 0.18 DDD/100,000 patient-days, while the occurrence of QRPA fell from 1.5 to 0/1,000 patient-days (figure, r = 0.84, P = 0.004). CONCLUSION: These longitudinal data, collected consistently over 9 years, clearly demonstrate a significant correlation between broad-spectrum antibiotic use and the occurrence of multidrug-resistant organisms in a MICU. A steep, linear decline in antibiotic use was correlated with a parallel fall in these 6 organisms. These data demonstrate that sustained, meaningful reductions in antimicrobial utilization in a MICU can result in significant reductions in the incidence of antimicrobial-resistant pathogens. [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.