An enzyme immunoassay for serum tobramycin

Area of Science:

• Clinical Chemistry
• Biochemistry
• Immunology

Background:

• Therapeutic drug monitoring (TDM) is crucial for optimizing antibiotic efficacy and minimizing toxicity.
• Accurate quantification of serum tobramycin is essential for patients receiving this aminoglycoside antibiotic.
• Existing methods for tobramycin measurement may have limitations in sensitivity, cost, or ease of use.

Purpose of the Study:

• To develop and validate a novel heterogeneous enzyme immunoassay for the precise determination of serum tobramycin concentrations.
• To evaluate the sensitivity, accuracy, and precision of the developed enzyme immunoassay.
• To compare the performance of the new assay with established methods like radioimmunoassay and bioassay.

Main Methods:

• A heterogeneous enzyme immunoassay was designed utilizing a tobramycin-beta-D-galactosidase conjugate as the labeled antigen.
• 4-methylumbelliferyl-beta-D-galactoside served as the fluorescence substrate for signal detection.
• Separation of bound and free fractions was achieved using an immobilized second antibody (Immunobead) system.

Main Results:

• The developed enzyme immunoassay demonstrated a minimal detectable level of 10 pg/tube (0.2 microgram/ml of serum).
• Excellent assay recovery was observed, with low intra-assay (4.41%) and inter-assay (12.6%) variances.
• Results obtained from the enzyme immunoassay showed strong agreement with those from radioimmunoassay and bioassay.

Conclusions:

• The developed enzyme immunoassay is a highly sensitive and reliable method for quantifying serum tobramycin.
• This assay system offers a practical and accurate approach for therapeutic drug monitoring of tobramycin.
• The assay's design principles are adaptable for developing similar immunoassays for other drugs and hormones.