Make Sense of Antibiotics-A Scientific Approach to Understand Food Safety


Why are “antibiotics” found in our food?

Antibiotics are a class of secondary metabolites, with anti-pathogenic properties or other active ingredients, produced by microorganisms (including bacteria, fungi and actinomyces), higher plants or higher animals during their growth and development. These chemical substances can inhibit or kill other microorganisms. First introduced in the 1940s, antibiotics have not only been widely used in human medicine, but also in veterinary treatment. They are used in treating diseased humans as well as sick food animals (including livestock and aquatic food products).


However, according to the World Health Organization (WHO), more than half of the current antibiotic production is used in agriculture, which encompasses the rearing of food animals. Hence, the rational use of antibiotics is worthy of concern.


What are the principles of the use of “antibiotics”?

With the administration of antibiotics, many contagious diseases in food animals came under control and are treated during the rearing process. However, antibiotics must be used rationally and in compliance with regulations so as to effectively protect animal health and avoid economic losses by lowering the risk of large-scale death of food animals caused by epidemics. In the long run, it helps to ensure the stable supply of food animals and promote food safety.


  The World Organisation for Animal Health (OIE), World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO) unanimously advocate the prudent and responsible use of medicine including antibiotics in food animals. Antibiotics should only be used under veterinary supervision when administered to animals and only when it is medically necessary. Each type of infectious disease has its own etiology and each type of antibiotic has its scope of application. Antibiotics can be administered based on clinical experience, but in case of doubt, antimicrobial susceptibility tests on the pathogenic bacterium should be performed to determine which antibiotic is suitable for effective treatment of the disease. Antibiotics should not be used randomly on food animals or without veterinary prescription and supervision.


Moreover, the requirements governing the “withdrawal period” stipulated in the “Veterinary Pharmacopoeia” must be strictly obeyed. Scientific evidence confirmed that antibiotic residues in food animals can be reduced to acceptable levels by strict compliance with the “withdrawal period”. By and large, the use of antibiotics on the rearing of food animals is not completely ruled out but requires strict compliance with the regulations governing the use of veterinary antibiotics (conditions of use, dosage and withdrawal period, etc.). 


What are the regulatory provisions on “antibiotics”, veterinary medicine and prohibited substances in Macao?

  The use of “antibiotics” and other veterinary medicine is intended to protect human health and interests and is subject to stringent control. According to the “Food Safety Law” as well as Administrative Regulation No.6/2014 “List of Prohibited Substances in Food” amended by Administrative Regulation No.3/2016, malachite green, chloramphenicol and nitrofurans are classified as prohibited substances for use in foods. All food products for sale in Macao must be free of these substances. Any offence related to the use of the prohibited substances in food shall be punishable in accordance with the law. Furthermore, the Administrative Regulation No.13/2013 “Maximum Limits of Veterinary Drug Residues in Food” stipulates the maximum residue limit of 10 categories of medicine, encompassing 18 types of veterinary medicine, in different species of food animals, such as cows, pigs, chickens, ducks, sheep, fish and shrimp, etc. For details of the aforesaid law and regulations, please refer to the Food Safety Information Website and government notices.