A broad range of antibiotics are used in animal production including beta-lactams, cephalosporin’s, tetracycline’s, sulphonamides, amino glycosides, macrolides . Residues of veterinary drugs have been recognized as an important aspect of food safety because residues may persist for longer periods after withdrawal of the drug treatment. Antibiotics are also used as feed additives to promote growth, improve feed efficiency and synchronize the reproductive cycle and breeding performance which may further lead to residual toxicity. Most of the antibiotics used in food animals are the same as or belong to the same classes as those used in humans. It has been found that the use of antibiotics to promote growth in livestock has led to the production of resistant strains of microorganisms which can transmit this resistance to other bacteria.
Antibiotics are used largely for three purposes in animal’s therapeutic use, prophylactic use and as growth promoters to improve feed utilization and production. Antimicrobial growth promoters are used to help the animals to digest their food more efficiently, get maximum benefit from it and allow them to develop into healthy individuals. AGPs are typically administered in sub-therapeutic doses for long periods and sometimes for the entire duration of production cycle. Safe and effective use of antibiotic in animal production has received considerable attention in most of the countries in the world. The drug resistance has gained its importance due to the transmission of antibiotic resistance factor to other enteric organisms which have posed a serious public health problem. The antibiotic residues occur in food mainly as a result of therapeutic treatment for animals or supplementation of animal feed. A limited amount of these arise by the addition of these antibiotics in preservation of milk, meat, fish and poultry. Microbial resistance to antibiotics results from prolonged ingestion of small amount of contaminated food. Variety of the antibiotics used to treat bacterial infections in humans has veterinary applications: prophylactics and growth promoters. In these two cases, the antibiotics are used at concentrations lower than the therapeutics concentrations for a longer period of time, a potentially dangerous practice. It is one of the strongest selective pressures leading to emergence of antibiotic resistance strains of bacteria, induction of allergic reactions in humans and technological problems of fermented meat products. The frequent use of antibiotics may result in drug residues that can be found at different concentration levels in products from animal origin such as milk or meat. Existence of antibiotic residues in food stuff can pose hazards to human health. Chloromycetine although a useful antibiotic, has been proved as one of the most perilous because it has been considered responsible for fatal blood Dyscrasias. It has also been regarded as toxic to premature infants.
Antibiotics are used largely for three purposes in animal’s therapeutic use, prophylactic use and as growth promoters to improve feed utilization and production. Antimicrobial growth promoters are used to help the animals to digest their food more efficiently, get maximum benefit from it and allow them to develop into healthy individuals. AGPs are typically administered in sub-therapeutic doses for long periods and sometimes for the entire duration of production cycle. Safe and effective use of antibiotic in animal production has received considerable attention in most of the countries in the world. The drug resistance has gained its importance due to the transmission of antibiotic resistance factor to other enteric organisms which have posed a serious public health problem.
Antibiotic residues in poultry & aquaculture
Poultry industry is the largest supplier of animal protein in the form of meat and eggs. In poultry, practice of antibiotics had facilitated their efficient production and also enhanced the health and well being of poultry by reducing the incidences of diseases but unfortunately, unauthorized use of these antibiotics, the failure to follow label directions or inappropriate withdrawal period of time before slaughtering of poultry could lead to contamination of edible poultry tissues with antibiotic residues, with potential adverse effect on human health .There are two ways in which the antibiotics in feed can affect human health, the direct effect of the residues in poultry meat and eggs and the indirect effect resulting from the selection of antibiotic resistant strains of pathogenic bacteria.. Antibiotic residues in foods of animal origin are one of the sources of concern among the public and medical health professionals. As aquaculture has developed, a range of fish and shellfish diseases have been encountered that have led to major economic losses leading to failure of the viable industry in some parts of the world. This has lead to the increased use of veterinary drugs, antibiotics and vaccines in intensive production systems to combat disease. They are commonly used as feed medications or surface coated onto feed pellets and dispersed in the water. Malachite green, the anti-fungal, is a serious matter. HPLC is a technique which is employed for the detection and analysis of drug residues in case of fish.
Antibiotic residues in milk
Antibiotic residue in milk product had been observed due to indiscriminate use of various antibiotics to treat mastitis. Antibiotics used as therapeutic agents or as feed supplement in milch animal lead to secretion of their residue in milk .These residues not only create problems in dairy industry but also have immense public health significance. Secondly, the ingestion of antibiotic contaminated milk may cause a reaction in humans already sensitized to the contaminants. The potential hazards include allergic reactions, interference in the intestinal flora & resistance population of bacteria in the general population. Small levels of antibiotics can be very hazardous to susceptible humans causing acute to severe reaction. The most common causes of occurrence of drug residues in milk are insufficient identification of treated cows, insufficient knowledge about withdrawal periods and failures due to hired staff. Pathological effects produced by Antibiotic Residues in Food include autoimmunity, Carcinogenicity, Mutagenicity, hepatotoxicity, reproductive disorders, bone marrow toxicity, allergy, leucocytosis, atypical lymphocytes, lung congestion, toxic granulation of granulocytes and thrombocytopenia. Liver injury and delayed blood coagulation may also occur. It can damage calcium rich organs like teeth and bones and sometimes erosion of nasal cavities. Children under 7 years of age may develop a brown discoloration of the teeth. Antibiotic resistance is a threat to human health and a global public health concern today. The U.S. Centers for Disease Control and Prevention has described resistance as one of the world’s most pressing health problems. The WHO has identified antibiotic resistance as one of the three greatest threats to human health. Many well known antibiotics are no longer effective to treat common infections such as otitis, pneumonia, gonorrhea and tuberculosis. Thus, microbial resistance is the main cause of newly emerging and reemerging infectious diseases. The WHO has recommended that antibiotics which are also licensed in human medicine should not be used any more as growth promoters in livestock.
Alternative treatments & Residues Prevention
It includes use of probiotics in aquaculture. Use of essential oils, from plants generally recognized as safe substances. These oils may constitute alternative prophylactic and therapeutic agents in aquaculture. Phage therapy has gained much attention for its advantages in preventing and controlling pathogen infections. The first step in residue prevention is to make individuals & organizations well aware of the problem through education by veterinary personnel, organizations & literatures and Governmental agencies .Then rapid screening procedures should be followed for the analysis of antibiotic residues and instant grading and prohibition of food containing antibiotics more than maximum residual limit. In case of milk, processing should be practiced for the inactivation of antibiotics. In case of penicillin the process of refrigeration should be used for its disappearance. Also in pasteurization most of antibiotics will lose activity. Use of activated charcoal, resin and UV irradiation also help for antibiotic inactivation. Irrational use of antibiotics in veterinary field practices should be avoided. Development of simple and economic field test to identify drug residues in edible animal products. Ethno-veterinary practices may be promoted and nationwide monitoring and periodic surveillance of microbial residue in edible tissues and milk should be practiced.