2184. Clinical and Molecular Epidemiology of Carbapenem-Resistant Gram-Negative Bacilli in a Los Angeles Tertiary Medical Center

Abstract Background Multidrug-resistant gram-negative bacilli are a significant public health threat, associated with 2.2 million deaths worldwide. Of particular importance is the rise of carbapenem-resistant gram-negative bacilli (CRGNB) given the limited options for treatment. The 30-day mortality associated with carbapenem-resistant Pseudomonas aeruginosa, carbapenem-resistant Enterobacterales, and carbapenem-resistant Acinetobacter baumannii ranges from 16 to 24%. In recognition of the substantial danger of these organisms, the World Health Organization has designated three CRGNB as Critical Priority pathogens. Methods Based on culture data and antimicrobial susceptibility testing, patients with CRGNB at Cedars-Sinai Medical Center from December 2022 to April 2023 were identified. Clinical data including patient demographics, prior carbapenem use, isolation of additional antibiotic-resistant organisms, subsequent antibiotic therapy, and mortality were compared among CRGNB. Results Of over 65 isolates, the largest proportion of isolates were cultured from pulmonary sources (44%), followed by urine (34%), skin (12%), blood (6%), and abdominal sources (4%). The most prevalent CRGNB isolated were Pseudomonas aeruginosa (65%), Escherichia coli (13%), and Klebsiella pneumoniae (7%). A majority of patients with CRGNB had prior documented carbapenem use (74%) and 71% of CRGNB were associated with at least one other antibiotic resistant organism. Cefiderocol was used to treat 12% of cases. However, 24% of CRGNB were not treated with antibiotics, often with the rationale that the isolate was likely a colonizing strain. The mortality rate among patients with CRGNB during our observation period was 18%. Conclusion CRGNB are emerging pathogens associated with prior carbapenem use and result in significant mortality. Subsets of organisms from our dataset will be further studied for relatedness using Fourier-Transform infrared spectroscopy and whole genome sequencing. Disclosures All Authors: No reported disclosures