Development and Validation of an LC-MS/MS Method for Simultaneous Determination of 12 Antibiotics in Human Serum.

PURPOSE: To develop and validate a high-throughput LC-MS/MS method for simultaneous quantification of 12 clinically important antibiotics, addressing current limitations in multi-class therapeutic drug monitoring (TDM), particularly for β-lactam/β-lactamase inhibitor combinations. METHODS: A validated LC-MS/MS method was established using isotope-labeled internal standards. A total of 200 clinical serum samples were analyzed. Method performance was evaluated in accordance with CLSI C62 guidelines, including linearity, lower limits of detection (LLOD), lower limits of quantification (LLOQ), selectivity, accuracy, precision, matrix effects, carryover, interference, dilution effect and stability. RESULTS: All analytes showed excellent linearity (R2 ≥ 0.9938), with acceptable accuracy (87.01%-112.73%) and precision (<10% CV). Significant matrix-related interference was observed for imipenem, tigecycline, and vancomycin under hemolytic conditions, highlighting analyte-specific limitations. Clinical TDM results revealed that only 51.5% of patients achieved target therapeutic concentrations, while 48.5% were outside the recommended range. CONCLUSION: This method provides a robust analytical platform for multi-antibiotic TDM. Importantly, clinical data demonstrate substantial variability in empirical dosing, supporting the need for concentration-guided antimicrobial therapy. However, further external validation and outcome-based studies are required before routine clinical implementation.