[Evaluation of enzyme multiplied immunoassay technique for gentamicin assay. Comparison with bioassay]

To assess an enzyme multiplied immunoassay technique (EMIT) for determination of gentamicin, comparison was done with a microbiological bioassay. Twenty-nine samples from 5 patients and 1 volunteer were assayed by both EMIT and bioassay methods. Concentrations of gentamicin obtained with EMIT were compared with those with bioassay. Statistical calculation resulted in a regression line with a correlation coefficient of 0.9496, a slope of 0.735 and an ordinate intercept of 0.878. To test the specificity of EMIT, serum controls which contain a constant quantity of gentamicin and a variable quantity of ampicillin concomitantly were assayed for gentamicin concentrations by both EMIT and bioassay. This test demonstrated that EMIT is free from interference of ampicillin while bioassay is vulnerable to interference. To conclude, EMIT proved to be a practical alternative to current bioassays for determination of serum gentamicin concentrations.