A sensitive bioassay for teicoplanin in serum in the presence or absence of other antibiotics

Area of Science:

• Microbiology
• Clinical Chemistry
• Pharmaceutical Analysis

Background:

• Teicoplanin is a crucial glycopeptide antibiotic used to treat serious Gram-positive bacterial infections.
• Accurate therapeutic drug monitoring is essential for optimizing teicoplanin efficacy and minimizing toxicity.
• Existing bioassays may face interference from co-administered antimicrobial agents.

Purpose of the Study:

• To develop and validate a novel, sensitive, and reliable bioassay for quantifying teicoplanin concentrations in human serum.
• To establish the assay's performance characteristics, including linearity, sensitivity, and accuracy.
• To assess the assay's compatibility with commonly used antibiotics.

Main Methods:

• Development of a specific assay medium (Mueller-Hinton II Agar base with NaCl, CaCl2, citric acid) and selection of Bacillus subtilis ATCC 6633 as the indicator organism.
• Utilizing the zone of inhibition method with either agar wells or paper filter disks to measure teicoplanin concentration.
• Establishing a linear relationship between the log10 teicoplanin concentration and the zone diameter in human serum.

Main Results:

• The developed bioassay demonstrated accurate and sensitive performance across a teicoplanin concentration range of 0.15 to 96 µg/ml.
• A clear linear correlation was observed between the zone of inhibition diameter and the logarithm of teicoplanin concentration.
• The assay proved effective in the presence of aminoglycosides and beta-lactams (after beta-lactamase inactivation).

Conclusions:

• A robust and reliable teicoplanin bioassay has been successfully developed.
• The assay is suitable for therapeutic drug monitoring of teicoplanin in human serum.
• The method shows potential for use alongside other antibiotics, including rifampin with a resistant bacterial strain.