Environmental contamination by antibiotics, fueled by industrial-scale use in animal production in some countries, is a global problem that must be addressed, according to the authors of a recently published study .
The global challenge is to reduce and improve the use of antibiotics, wrote Lizbeth Robles-Jimenez and her fellow researchers in the journal Animals.
The review team set out to review previously published research on antibiotic residues, to assess the use of these drugs in animal production and their excretion in animal products, as well as in water and soil.
Antibiotics are widely used in some parts of the world for the treatment of disease, protection of health, and as growth promoters in animal production.
The authors noted that the absorption of antibiotics in animals after administration is often poor and that a significant proportion, 70-90%, can be excreted without being metabolized. “These residues remain unchanged in the environment.”
The authors found 165 published studies in total, reporting the concentration of antibiotic residues found in the environment, livestock (cow, sheep, pig, horse, chicken, rabbit, goat), tissues of aquatic and terrestrial animals. , animal products (milk and eggs), wastewater and soil. Articles were obtained from Asia, Africa, North America, South America, Europe and Oceania.
The biggest users of veterinary antibiotics in the world are China (45%), Brazil (7.9%), United States (7.0%), Thailand (4.2%), India (2.2%), Iran (1.9%), Spain (1.9%), Russia (1.8%), Mexico (1.7%), and Argentina (1.5%).
The review team said the continent-based antibiotic residue levels showed marked variability between antimicrobial families.
The antimicrobial with the highest concentration in Asia was cephalosporins, followed by fluroquinolone.
Tetracyclines were the family of antibiotics with the highest residual concentration in Africa and North America. In South America, the family of antibiotics with the highest level of residues were fluroquinolones, followed by macrolides.
In Europe, the highest concentration of residues was shown by β-lactam, followed by nitroimidazole.
“It is important to note,” they said, “that there is a particular distribution of antibiotic use by geographic area depending on their policies, economic / market conditions and dietary habits.”
The authors noted that the regulation of antibiotics in animal feed, for growth promotion or therapeutic use, is a priority for the Asian region, and policies for their ban have been developed. However, few countries have the capacity to guarantee their application.
The Chinese government has put in place a series of policies to control the use of antibiotics in livestock, including the requirement for a prescription. However, they are still bought without a prescription and are not monitored on most farms.
In Russia, farmers can use antibiotics without any restrictions, while some food antibiotics are subject to state control.
The researchers noted that an improvement in the standard of living in India had led to a demand for animal protein resulting in an intensification of the breeding of pigs, poultry and fish, with a significant effect on the use of antibiotics.
“When we talk about meat producers, we have to mention the main world meat producers, North and South America, who are also among the main consumers of veterinary antibiotics.
“For example, the United States uses 24.6 million pounds of antimicrobials for non-therapeutic purposes in chickens, cattle and pigs, the most commonly used being tetracyclines, penicillins, fluroquinolones and sulfa drugs,” and Brazil, being the world’s fourth largest pork producer, uses sulfonamides.
“However, although government agencies are trying to regulate the use of antibiotics, producers are unwilling to stop using them because they believe that it would be impossible to sustain current market demands without the use of antibiotics. antimicrobials.
“In our study, we can confirm this since most of the articles found on antibiotic residues came from the United States and Mexico. Although Brazil is one of the largest producers of meat, only one article was found, which may be due to the lack of published reports and complex political barriers.
The researchers said that although most countries have joined the program of non-abuse of antibiotics in food animals, the publication of reports, complex political, economic and social barriers still limit the quality of drugs. data on this issue.
Data on the use of antibiotics are more readily available in countries which export a large part of their animal production than in countries where the majority of production is destined for the domestic market.
The authors stated that there is environmental pressure on microorganisms in soil and water in the event of antibiotic contamination, forcing selection on reducing the diversity and composition of the microbial community.
“Considering that exposure to antibiotics tends to promote an increase in Gram-negative bacteria over Gram-positive bacteria, this will lead to the disruption or loss of bacteria that play key ecological roles such as the breakdown of matter, ”they said.
They recognized that new international policies have limited the use of antibiotics as therapeutics, restricting their use as growth promoters in animal production.
“Intensive animal production needs to change, as it would be impossible to sustain current market demands without the use of antimicrobials or more user-friendly alternatives, with future decrease in antimicrobial resistance, so we are challenged to reduce their use.
“At present, despite increasing trends in regulations on the use of antibiotics around the world, antibiotics are still used in the production of food animals and are present in water and floor. “
The abuse of antibiotics continues in many countries, they said. “We need to realize that contamination by antibiotics is a global problem, and we are challenged to reduce and improve their use.”
The review team, drawn from various institutions, including the Autonomous University of the State of Mexico, was composed of Robles-Jimenez, Edgar Aranda-Aguirre, Octavio Castelan-Ortega, Beatriz Shettino-Bermudez, Rutilio Ortiz-Salinas , Marta Miranda, Xunde Li, Juan Angeles-Hernandez, Einar Vargas-Bello-Pérez and Manuel Gonzalez-Ronquillo.
Robles-Jimenez, LE; Aranda-Aguirre, E .; Castelan-Ortega, OA; Shettino-Bermudez, BS; Ortiz-Salinas, R .; Miranda, M.; Li, X.; Angeles-Hernandez, JC; Vargas-Bello-Pérez, E .; Gonzalez-Ronquillo, M. Global traceability of antibiotic residues from livestock in wastewater and soil: a systematic review. Animals 2022, 12, 60. https://doi.org/10.3390/ani12010060