BACKGROUND: Recent studies indicate that a high proportion of patients in the intensive care unit (ICU) fail to attain adequate antibiotic levels. Thus, there is a need to monitor the antibiotic concentration to ensure effective treatment. Herein, the authors aimed to develop an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the simultaneous quantification of antimicrobials to assess individualized therapeutic drug monitoring (TDM).

METHODS: A UHPLC-MS/MS method with 11 antibiotics (ciprofloxacin, moxifloxacin, benzylpenicillin, levofloxacin, linezolid, rifampicin, meropenem, cloxacillin, cefotaxime, clindamycin, and piperacillin) was developed. Chromatographic separation was performed using a Kinetex biphenyl reversed-phase column, with gradient elution using 0.1% formic acid (FA) and methanol with 0.1% FA. Sample preparation was performed using methanol protein precipitation. The total run time was 5 min.

RESULTS: For all analytes, the inter-assay inaccuracies for calibrators were ≤5%. The inter-day inaccuracies for the quality controls (QCs) were ≤5% for all analytes. The inter-assay precision for calibration standards ranged between 1.42% and 6.11%. The inter-assay imprecision for QCs of all antibiotics and concentrations ranged between 3.60% and 16.1%. Inter-assay inaccuracy and imprecision for the QCs and calibration standards were ≤15% for all drugs, except benzylpenicillin.

CONCLUSION: A rapid UHPLC-MS/MS method was developed for the simultaneous quantification of 11 different antibiotics. Minimal sample preparation was required to ensure a rapid turnaround time. The method was applied to clinical samples collected from four ICUs.