Discussion
This study provides a microsampling TDM platform validated for clinical use for a rapid quantification of three antibiotics and is suitable for real-time TDM-guided personalization of antimicrobial treatment in critically ill children.
Methods
Paired DBS and CMS samples were obtained from an intensive care unit (ICU) to evaluate its clinical application. Estimated plasma concentrations (EPC) were calculated from DBS concentrations. Agreement between methods was evaluated using Deming regression and Bland-Altman difference plots.
Results
The microsampling methods validation showed excellent reliability and compatibility with the analysis of the sample matrix and hematocrit range of the studied population. The DBS and CMS accuracy and precision results were within accepted ranges and samples were stable at room temperature for at least 2 days and 8 h, respectively. Hematocrit had no impact on CMS, but sightly impacted DBS measurements. The CMS and DBS antibiotic concentrations correlated well (r > 0.98). The drug concentration ratio in DBS samples to that in CMS was 1.39 for vancomycin, 1.34 for meropenem, and 0.94 for linezolid. The EPC calculated from the DBS using individual hematocrit ranges presented comparable absolute values for vancomycin (slope: 1.06) and meropenem (slope: 1.04), with a mean of 98% and 99% of the measured CMS concentrations, respectively.