Measurement of amikacin in serum by a latex agglutination inhibition test

Levels of amikacin in serum were determined in 106 serum specimens by a latex agglutination inhibition card test and by radioimmunoassay (RIA). Linear regression analysis demonstrated a high degree of correlation between the two assays (latex = 0.95 (RIA) + 0.69; r = 0.97). Assay of three control sera containing 7.5, 15, and 30 micrograms of amikacin per ml on 7 separate days showed good reproducibility with a coefficient of variation of 0 to 11.7% for the latex assay compared with 7.01 to 22.2% for RIA. Recovery of amikacin in spiked sera varied between 93 and 108% for the latex assay compared with 90 and 100% for RIA. Because the procedure involves a titer, the latex agglutination inhibition card test produces results which are categorized rather than results which are continuous. However, it is a rapid and specific method for determining amikacin levels in clinical specimens and is particularly useful when processing small numbers of specimens.