385: Optimizing Icu Empiric Coverage: Five-Year Review of Antibiotic Resistance Trends in Gram-Negatives

Introduction: Empiric antimicrobial selection in the ICU requires accurate, up-to-date knowledge of local resistance patterns. Traditional hospital-wide antibiograms often fail to capture ICU-specific trends, potentially leading to suboptimal empiric coverage. Additionally, CLSI’s 2024 removal of amikacin as a preferred agent for Pseudomonas aeruginosa necessitates reassessment of aminoglycoside use. We analyzed five years of ICU-specific antibiograms to evaluate resistance trends and guide empiric therapy strategies. Methods: Antibiotic susceptibility data were extracted from annual ICU antibiograms (2018–2022) at a community-based tertiary hospital. Key pathogens included Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. For Gram-negative organisms, ESBL and non-ESBL isolates were combined. Oxacillin susceptibility served as a surrogate for MRSA prevalence. Following CLSI updates, tobramycin was used in place of amikacin for P. aeruginosa. Linear regression was used to assess trends, with significance set at p< 0.05. Results: A total of 1,292 ICU isolates were analyzed. Staphylococcus aureus showed persistently low oxacillin susceptibility (0–3%), indicating high MRSA prevalence. Escherichia coli exhibited a significant decline in cefepime (88% to 73%, p=0.03) and levofloxacin susceptibility (84% to 62%, p=0.01). Klebsiella pneumoniae demonstrated modest, nonsignificant declines in cefepime (91% to 81%, p=0.06) and levofloxacin (92% to 87%, p=0.09). Pseudomonas aeruginosa maintained high tobramycin susceptibility (90–98%, p=0.47) across all years. Conclusions: ICU-specific resistance trends differ significantly from hospital-wide data. Declining susceptibility in E. coli and K. pneumoniae raises concerns about the reliability of cefepime and levofloxacin as monotherapy. P. aeruginosa retains high susceptibility to tobramycin, while persistently low oxacillin susceptibility supports ongoing MRSA coverage. This study highlights the need for ICU-level antibiogram review and stewardship-informed empiric protocols. Limitations include its retrospective, observational, single-center design and relatively small sample size, which may affect generalizability.