Evaluation of Innofluor fluorescence polarization immunoassay kits for the determination of serum concentrations of gentamicin, tobramycin, amikacin and vancomycin.lesassays@ukneqasaa.win-uk.net.

The Innofluor fluorescence polarization immunoassay (FPIA) kits for gentamicin, tobramycin, amikacin and vancomycin were evaluated on an Abbott TDX analyser. Intra-assay reproducibility was excellent with a coefficient of variation of <3% for all analytes. The coefficient of variation for inter-assay reproducibility was usually <5%. Assay linearity was good and standard curve stability was seen with kits of the same batch for at least 32 days. Using clinical samples, the results obtained with the Innofluor FPIA reagents correlated well with those obtained using Abbott FPIA reagents, but Innofluor gentamicin and amikacin results were slightly higher than Abbott results (P < 0.001). Results of UK NEQAS returns showed acceptable accuracy for the Innofluor kits, but mean Innofluor gentamicin returns were 4% higher (P = 0.001) and mean vancomycin returns were 5% lower (P = 0.001) than overall mean returns. Innofluor and Abbott vancomycin assay reagents showed similar cross-reactivity to degraded vancomycin.