Comparison of fluorescence polarization immunoassay and high-performance liquid chromatography methods for assay of teicoplanin: can correlation be improved?

Abstract

Teicoplanin is a glycopeptide indicated in serious infections due to Staphylococcus aureus and requires monitoring and dose adjustment based on measurement of trough concentration. Measurement of teicoplanin can be carried out by the fluorescence polarization immunoassay (FPIA) method or by high-performance liquid chromatography (HPLC) methods. We aimed to compare HPLC method using the sum of the peaks of A2-2, A2-3, A2-4 and A2-5 with FPIA method. Thirty-six serum samples obtained over a 6-month period from patients treated by teicoplanin were first analyzed by a HPLC method by determining both the A2-2 peak and the sum of areas of A2-2 to A2-5 and were then stored at –20 °C for FPIA assay. Correlation between FPIA and HPLC A2-2 methods was as: HPLC A2-2 = 0.694FPIA – 0.892 with r 2 = 0.93. A paired t-test revealed significant differences between the results ( P < 0.001). To improve the FPIA and HPLC correlation, we performed a linear regression between FPIA and the sum of A2-2, A2-3, A2-4 and A2-5 obtained in the HPLC method: HPLC A2-2 to A2-5 = 0.953FPIA – 0.915 with r 2 = 0.96. A paired t-test did not show any significant difference between the results of the two methods ( P = 0.94). These results show a better correlation between FPIA and HPLC when the sum of A2-2 to A2-5 was used for calculations. In conclusion, HPLC A2-2 to A2-5 must be preferred to HPLC A2-2 for the assay of teicoplanin, even if the HPLC A2-2 to A2-5 runtime is higher than in the HPLC A2-2 method.