Evaluating rapid antimicrobial susceptibility testing directly from positive blood cultures for Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa in Chinese hospitals.

Introduction: We sought to assess whether rapid antimicrobial susceptibility testing (AST) directly from positive blood culture bottles for Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa can be used in Chinese hospitals.

Methods: Rapid AST was performed on each positive blood culture bottle. Categorical rapid AST results at 8 to 10 and 16 to 18 hours were compared with those from the VITEK 2 system (bioMérieux). Minimum inhibitory concentrations and zone diameter were interpreted according to Clinical and Laboratory Standards Institute (CLSI) standard M100-S34, published in 2024.

Results: At 8 to 10 hours, the overall categorical agreement for E coli, K pneumoniae, and P aeruginosa was 99.1%, 98.4%, and 95.8%, respectively. At 16 to 18 hours, these rates were 97.4%, 98.9%, and 99.1%, respectively. For E coli, the categorical agreement ranged from 97.2% (ceftazidime at 8-10 hours) to 100% (ampicillin and meropenem at 8-10 and 16-18 hours and ciprofloxacin at 16-18 hours). The categorical agreement for K pneumoniae varied from 96.5%with ceftazidime at 8 to 10 hours to 100% with meropenem and ciprofloxacin at 16 to 18 hours. For P aeruginosa, the categorical agreement ranged from 93.7% (meropenem at 8-10 hours) to 100% (ciprofloxacin at 16-18 hours).

Discussion: The CLSI rapid AST method is reliable for E coli, K pneumoniae, and P aeruginosa in Chinese hospitals.