520. Development of Cefepime-taniborbactam MIC Antimicrobial Susceptibility Test (AST) for Enterobacterales and Pseudomonas aeruginosa on MicroScan Dried Gram-negative MIC Panels

Abstract Background Automated AST devices are critical to inform appropriate care of patients with bacterial infections. Cefepime-taniborbactam is an investigational agent under development to treat infections due to multidrug-resistant bacteria, including carbapenem-resistant Enterobacterales and Pseudomonas aeruginosa. Development of a cefepime-taniborbactam antimicrobial susceptibility test was completed for the MicroScan Dried Gram-negative MIC (MSDGN) Panel when compared to CLSI broth microdilution reference panels. Methods Development was conducted by comparing MICs obtained using the MSDGN panel to MICs using a CLSI broth microdilution reference panel. The concentration range of cefepime-taniborbactam evaluated was 0.12/4-64/4 µg/mL. A total of 1376 isolates (1256 Enterobacterales and 120 P. aeruginosa) were tested at 16, 18, and 20 hours incubation times (for visual read and autoSCAN-4). A total of 917 isolates (837 Enterobacterales and 80 P. aeruginosa) were tested at 16 and 18 hours incubation time for the WalkAway System. All isolates were tested using turbidity and Prompt® methods of inoculation. MSDGN panels were incubated at 35 ± 1°C. Reference panels, prepared according to ISO methodology, were inoculated using the turbidity inoculation method. All frozen reference panels were incubated at 35 ± 2°C and read visually. Rates of essential agreement (MicroScan MIC within ± 1 doubling dilution of reference MIC) were determined for each combination of inoculation method and read method. Results Essential agreement rates ranged from 93.0% to 98.8% for all isolates tested during development. Essential agreement rates for each inoculation and read method are presented in Table 1. Table 1- Results Conclusion Cefepime-taniborbactam MIC results obtained with the MSDGN panel correlated well with MIC results obtained using reference panels. Rates of essential agreement were ≥93.0% for all inoculation and read methods. These development data support the continued evaluation of MSDGN panel with cefepime-taniborbactam in a multicenter trial. Pending submission and clearance by the United States Food and Drug Administration; not yet available for in vitro diagnostic use in the US. For Investigational Use Only. The performance characteristics of this product have not been established. Disclosures Enrique J. Fernandez, BS, Beckman Coulter, Inc.: Employee of Beckman Coulter Robert L. Williams, PhD, Beckman Coulter, Inc.: Employee of Beckman Coulter Vasna Carr, BS, Beckman Coulter, Inc.: Employee of Beckman Coulter Vasna Carr, BS, Beckman Coulter, Inc.: Employee of Beckman Coulter Miller Renae, BS, Beckman Coulter, Inc.: Employee of Beckman Coulter.