Testing for Antibiotic Residues
For microbiological testing of animal products for the presence of antibiotic residues in accordance with GROVE and RANDALL (“Assay Methods of Antibiotics”, 1955), Merck offers several agars. These media comply with the recommendations of the United States Pharmacopeia XXVI (2003) and the FDA. In addition, Antibiotic agar no. 1 corresponds to Medium A of the European Pharmacopeia II.
The sample material can be tested by the dilution or the diffusion methods. The most commonly used method is the agar diffusion test which can be performed in various ways: cylinder, punched-hole or paper-disc tests (see application note for details).
Due to their low cost and easy availability, a significant number of antibiotics have been intensively used around the globe in various sectors of food production, including dairy, livestock, poultry and aquaculture.
Some antibiotics have been prohibited for use in food animal production by a number of countries, including Australia, Canada, USA and EU member states, due to concerns about their possible carcinogenicity and mutagenicity. By inhibiting the growth of a natural and useful microbial flora in some matrices (e.g. sausages), these antibiotics can actually lead to less competition and therefore to better growth conditions for some pathogenic organisms, in particular those which manage to build up resistence against specific antibiotics.