Antibiotic residues in food of animal origin such as milk, eggs or meat represent a potential health risk to the consumer. Therefore, R-Biopharm offers a broad portfolio of different test systems for the analysis of antibiotic residues.

Antibiotics are naturally formed metabolites derived from fungi or bacteria. Substances that do not occur in nature and are produced by modern biotechnology and chemical synthesis are called antibiotics as well. Antibiotics are able to kill microorganisms or inhibit their growth. In human and veterinary medicine, antibiotics are therefore used as drugs for the treatment of bacterial diseases.

Origin and health risks of antibiotic residues in food

The use of antibiotics as drugs for the treatment of diseased animals is a matter of animal welfare and therefore inevitable. As a result of application failures, such as non-compliance with the statutory waiting period or abuse as antibiotic growth promoter, residues of antibiotics can occur in food of animal origin such as meat, milk or eggs.

Due to the potentially carcinogenic and toxic properties of antibiotic residues and their allergic potential, the consumption of contaminated food establishes a direct risk for public health. Furthermore, the inappropriate use of antibiotics in animal husbandry and food production promotes the multi-drug resistance of pathogen bacteria for antibiotics used in human medicine. Antibiotic residues bear a risk for the production process safety and consequently also an economic risk, as they inhibit biotechnological production processes involving microorganisms such as starter cultures in the dairy industry.

Legal regulations

For reasons of consumer protection many countries established Maximum Residue Limits (MRLs) for pharmacologically active substances and monitor compliance in surveillance programs (Directive 96/23/EC; Regulation (EC) 470/2009 and 37/2010; Decision 2003/181/EC). In addition, the number of countries which prohibited the use of antibiotics as fattening agent is increasing.

Test systems for antibiotic drug residue analysis

RIDASCREEN® ELISA tests allow specific quantitative analysis of single antibiotics or antibiotic groups by immunological antibody-antigen recognition and readout by microtiter-plate photometer.EASI-EXTRACT® immunoaffinity columns offer improved sample clean-up and concentration of antibiotics from complex food matrices prior to analysis with HPLC or LC-MS/MS.Premi®Test, based on the growth inhibition of spores by antibiotics, offers a simple and cost-effective qualitative screening for a broad spectrum of antibiotics.

More information on specific antibiotics

R-Biopharm offers a portfolio of test systems for the analysis of many different antibiotics. Click on one of the following antibiotics to learn more about it.


Bacitracin belongs to the group of polypeptide antibiotics. It was named after the Bacillus strain producing it and the 7 year old girl ‘Tracy’ from whose open tibial fracture the strain was isolated in 1945 for the first time.

Bacitracin is a mixture of different polypeptides, wherein bacitracin A as major component has the highest biological activity. Through inhibition of cell wall synthesis, it has a broad spectrum bactericidal effect against both gram-positive and gram-negative bacteria. In addition to veterinary application, bacitracin can be used as antimicrobial growth promoter in animal husbandry. Thereby, residues can remain in foodstuff of animal origin and may pose a health risk to consumers. Improper use of antibiotics also promotes the formation of antibiotic resistant bacteria, which raise an increasing health problem for the population. Consequently, Bacitracin has been deleted by the regulation 2821/98/EC from the list of approved animal feed additives (Directive 70/524/EEG Appendix B) and maximum residue limits in foodstuffs have been set (Regulation 37/2010/EC).


The quinolones (or chinolones) are a family of synthetic broad-spectrum antibiotic drugs. They inhibit the gyrase enzyme and are therefore also known as gyrase inhibitors.

Gyrase inhibitors are divided into four subgroups. The majority of quinolones belong to the subgroup of fluoroquinolones, which have a fluoro-group attached at the central ring system, typically at the 6th position. The fluoroquinolones belong to the so called second generation quinolones. Some of these are admitted as antibiotics in veterinary medicine for food producing animals. Fluoroquinolones are broad spectrum antibiotics against a lot of bacterial species. They are used frequently in veterinary medicine especially for cattle, pigs and chicken. The usage of fluoroquinolones has increased in the past years because large amounts of these antibiotics were applied to prevent infectious diseases, especially in chicken, swine and fish/shrimp farming. The wide use in food producing animals has generated microbial resistances. This led to an amendment of Council Regulation (EEC) No 2377/90 and in the introduction of MRLs (Maximum Residue Limits) for some fluoroquinolones.


Chloramphenicol is a broad spectrum antibiotic which is frequently employed in animal production for its excellent antibacterial and pharmacokinetic properties. However, in humans it leads to hematotoxic side effects, in particular chloramphenicol-induced aplastic anaemia for which a dosage-effect relationship has not yet been established. This has led to a prohibition of chloramphenicol for the treatment of animals used for food production.

Chloramphenicol (2,2-dichloro-N-[(1R,2R)-1,3-dihydroxy-1-(4-nitrophenyl)propan-2-yl]acetamide), produced by Streptomyces venezuelae, was first discovered in 1947 and has been used in veterinary medicine since the 1950s. Today, the use of the broad spectrum antibiotic Chloramphenicol (CAP) is illegal for the administration in food-producing animals in the EU and many other countries worldwide. It is still frequently employed in animal production because of its excellent antibacterial and pharmacokinetic properties and low price. The mechanism of action of Chloramphenicol is bacteriostatic, inhibiting the protein synthesis in bacterial ribosomes. In humans, residues of CAP can cause myelosuppression (damaging the bone-marrow), and the potentially lethal chloramphenicol-induced aplastic anemia. No safe residue level could be established for these side effects. In order to ensure consumer health this led to a complete ban of chloramphenicol for the treatment of animals used for food production and a zero-tolerance for chloramphenicol residues. The EU established a Minimum Required Performance Limit (MRPL) for all test systems of 0.3 ppb.

The chemical structure of chloramphenicol has 8 different stereoisomers, of which only one (RR-p-CAP) is biologically active. The test kit it specific to this stereoisomer. The RIDASCREEN® Chloramphenicol quantitative ELISA is validated for a wide variety of matrices (milk, milk powder and milk products, honey, meat, fish, shrimp, eggs, feed, plasma and serum). In addition, the new version R1511 can also detect the metabolite chloramphenicol glucuronide, allowing for the direct screening of urine.


Nitrofurans are synthetic broad-spectrum antibiotics, which are frequently used in animal production due to their excellent antibacterial and pharmacokinetic properties. They have also been used as growth promoters during the production of shrimp, poultry and pigs.

Long term animal experiments have shown that the parent compounds and their metabolites have carcinogenic and mutagenic characteristics. This led to the prohibition of nitrofurans for the treatment of animals used for food production. In 1993, the EU banned the nitrofurans furaltadone, nitrofurantoin and nitrofurazone for use in animals used as sources of food, and in 1995 the use of furazolidone was also prohibited. The analysis of nitrofurans is based on the detection of the tissue bound metabolites of nitrofurans. The parent compounds are difficult to detect accurately since they are metabolized very rapidly after treatment. The tissue bound nitrofuran metabolites however are present for a long time after administration and they are used to detect nitrofuran abuse.

There are different types of nitrofurans:

  • Nitrofurantoin: 1-Aminohydantoin (AHD)
  • Furaltadone: 3-Amino-5-morpholinomethyl-2-oxazolidinone (AMOZ)
  • Furazolidone: 3-Amino-2-oxazolidinone (AOZ)
  • Nitrofurazone: Semicarbazide (SEM)

Prior to analysis, the metabolites have to be derivatized by incubation with 2-Nitrobenzaldehyde into NP-AHD, NP-AMOZ, NP-AOZ and NP-SEM.

β-Lactams (Penicillin)

β-Lactam antibiotics were named after their characteristic five-membered β Lactam ring and form a large group of antibiotics. They are classified by their chemical structure in several subgroups, whereas the most important ones are the penicillins, cephalosporins and carbapenems.

The penicillins were discovered accidentally in 1928 by Alexander Fleming and inhibit cell wall synthesis of gram positive bacteria. Despite their early discovery, they are still the most widely used group of antibiotics in the world. Especially for mastitis, a bacterial infection of the dairy cow udder, they are the first line treatment. For reasons of consumer protection and process safety in the dairy industry, in Commission Regulation (EU) No 37/2010 Maximum Residue Limits (MRLs) for 7 penicillins in food of animal origin were established.


Next to the ß-lactam antibiotics, in veterinary medicine, streptomycin is one of the mostly used antibiotics for the treatment of mastitis. Residues of streptomycin may therefore occur in food of animal origin, if the withholding period is not obeyed or if it is used improperly.

In high concentrations, streptomycin leads to ototoxic and nephrotoxic effects. The chronic exposure of humans with low concentrations, as found in food, may cause allergies, impair the intestinal flora and induce resistance of pathogenic microorganisms. To protect the consumer against healthy risks and avoid food-technological problems, a sensitive and simple method for the detection of streptomycin is necessary. The EU-regulations for streptomycin are specified in MRLs (maximum residue limits) for meat and milk (muscle and liver: 500 ppb, kidney: 1000 ppb, honey: 10 ppb and milk: 200 ppb).


Sulfonamides are widely used as feed additives, mainly for fattening of calves and pigs. Combined with inhibitors of dihydrofolate reductase such as trimethoprim, tetroxoprim, or pyrimethamine sulfonamides are also used in veterinary medicine for the treatment of intestinal infections, mastitis, pulmonitis and other (systemic) diseases. Sulfonamide residues may therefore occur in food of animal origin such as meat and milk. Particularly the transmission of the carcinogenic sulfamethazine represents a threat to human health. According to the EU law, a maximum residue limit (MRL) for all substances of the sulfonamide-group of 100 µg/kg (ppb) in muscle, fat, liver and kidney and of 100 µg/l (ppb) in milk is valid.


In 1948, aureomycin (chlortetracycline) was isolated by Duggan as a metabolite of the actinomyces species Streptomyces aureofaciens. This was the first antibiotic substance of the group of tetracyclines.

Worldwide, tetracycline, chlortetracycline and oxytetracycline are authorized for veterinary use. Therefore, health risks for the consumer can occur. In all animal species which are used for food production, tetracycline residues (the sum of mother substance and the 4-epimer) are limited in the EU law, commission regulation (EU) No 37/2010 with the following limits (MRLs): 100 ppb in muscle and in milk. The RIDASCREEN® Tetracyclin test can be used to detect tetracycline in milk and dairy products (cheese, butter, curd, yoghurt, kefir, cream, sour cream), meat and meat products as well as seafood, egg and honey.

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