Antimicrobial susceptibility patterns of Acinetobacter species at a reference laboratory and retrospective review of patients with positive blood cultures from a tertiary care center.

Acinetobacter is a pathogen of concern and is associated with significant antimicrobial resistance. Infections with Acinetobacter typically occur in healthcare settings. We reviewed the antimicrobial susceptibility results of Acinetobacter spp. isolates obtained from patients seen at our institution and isolates submitted from outside institutions to our laboratory for antimicrobial susceptibility testing (AST) from 12/1/2012 to 12/1/2022. Antimicrobial susceptibility was evaluated using agar dilution (disk diffusion for cefiderocol). For blood culture isolates from patients treated at our institution, a retrospective chart review was performed to describe clinical characteristics and outcomes. AST results from 4,689 Acinetobacter spp. isolates were included, and clinical data on bloodstream infection (BSI) were available for 83 patients from our institution. Isolates belonging to the A. baumannii-calcoaceticus complex exhibited <80% susceptibility to all antimicrobials tested. Isolates identified to the species level that did not belong to the A. baumannii-calcoaceticus complex displayed at least 90% susceptibility to ciprofloxacin, gentamicin, levofloxacin, meropenem, minocycline, and trimethoprim-sulfamethoxazole. These antimicrobials are likely to be active against non-baumannii-calcoaceticus complex Acinetobacter isolates. Among patients treated for BSI at our institution, immunocompromising conditions, vascular catheter sources, and polymicrobial cultures were common. A majority of patients had favorable clinical outcomes.