Fast determination of antibiotics in whole blood

• DOI: 10.1111/1469-0691.12074
• Publication Date: 2012-10-19T07:46:21Z
• Authors: Q. Chen; A. Andersson; M. Mecklenburg; B. Xie
• Keywords: Microbiology (medical); 0303 health sciences; Penicillin G; penicillinase; Biosensing Techniques; Penicillinase; biosensor; Anti-Bacterial Agents; critical care; 03 medical and health sciences; Infectious Diseases; Antibiotics; blood; Humans; Penicillin V; Ampicillin; Chromatography, High Pressure Liquid

There is a need for analytical methods capable of monitoring blood antibiotic levels in real time. Here we present a method for quantifying antibiotic levels in whole blood that does not require any sample pretreatment. The tests employ the enzyme penicillinase to assay for penicillin G, penicillin V and ampicillin using a flow-injected biosensor, the Enzyme Thermistor. Optimal flow rates, sample volumes and pH were determined to be 0.5 mL/min, 100 μL and 7.0, respectively. Analysis of the antibiotics diluted in buffer gave a linear range of 0.17-5.0 mM. Calibration curves prepared using blood spiked with the antibiotics gave a linear range of 0.17-2.0 mM. Linear regression values for all of the calibration curves were 0.998 or higher. Assay cycle time was 5 min. The relative standard deviation value for 100 determinations of a mock blood sample spiked with penicillin G was 6.71%. Despite the elimination of sample pretreatment, no detectable clogging or signal drift was observed. The assay provides a fast, simple, reliable analytical method for determining antibiotic concentrations in blood without the need for any sample pretreatment. This is an important first step towards developing a device capable of real-time monitoring of antibiotic levels in whole blood. The technology has the potential to significantly improve the outcomes of patients undergoing critical care.