Evaluation of four gentamicin and tobramycin assay procedures for clinical laboratories

Abstract

Accuracy, precision and clinical laboraotry utility of the TDX, Auto-ICS, COBAS-Bio with reagent kits and EMIT [enzyme-multiplied immuno technique] for gentamicin and tobramycin [antibacterial agents] serum assay were assessed. TDX, COBAS-Bio and EMIT analytical systems showed a proportional bias of < 10% for recovery studies and a coefficient of variation < 5% for within-run precision. The results of the recovery studies with the Auto-ICS showed a proportional bias of 25% with gentamicin and 16% with tobramycin. The within-run precision expressed as the coefficient of variation for the Auto-ICS was 6.7% for gentamicin and 8.6% for tobramycin. In comparisons involving gentamicin- and tobramycin-containing patient samples, the results with the TDX analytical system showed the best agreement with the COBAS-Bio. For the determination of these 2 antibiotics, the TDX analytical system provided the best overall accuracy and precision.