Antimicrobials have saved millions of humans’ lives, yet more than 70% of all antimicrobials on Earth are used on animals raised for food. They’re used in large volumes in intensive animal production systems to maintain the relative health and productivity of farmed animals who are confined in very close quarters.

The use of antimicrobials in animals raised for food has been linked with the rise of antimicrobial-resistant infections in animals and humans. For this reason, the World Health Organization (WHO) recommended the reduction of veterinary antimicrobial use in 2017. In low- and middle-income countries, higher antimicrobial-resistant levels could be reached by factors like lower biosecurity, the use of less nutritious feed, and looser regulation on veterinary drugs.

Meanwhile, the antimicrobial-resistant surveillance systems in low- and middle-income countries are elementary in comparison to those in high-income countries, and it could take a long time to build a global surveillance system. However, the consequences of antimicrobial resistance requires immediate action.

In this study, 901 “point prevalence” surveys reporting antimicrobial resistance rates in animals raised for food were used to map trends in low- and middle-income countries (the number of surveys in the Americas was limited, which resulted in low antimicrobial resistance levels). The analysis focused on resistance in Escherichia coli, Campylobacter spp., nontyphoidal Salmonella spp. and Staphylococcus aureus, since the number of published surveys on these pathogens increased greatly between 2000 and 2018 in low- and middle-income countries. 

The highest resistance rates were observed in the most commonly used classes of antimicrobials in animal production (etracyclines, sulfonamides, and penicillins) and in some antimicrobials considered critical to human medicine (ciprofloxacin, erythromycin, third- and fourth- generation cephalosporins). In low- and middle-income countries, from 2000 to 2018, the proportion of antimicrobials showing resistance above 50% increased in chickens and in pigs, and plateaued in cows (explained by the intensification of the operations of these species in comparison to cow farming). The largest hotspots of antimicrobial resistance were found in China and India, while new hotspots are emerging in Brazil and Kenya.

The authors provide a range of possible ways forward: in Asia, resistance levels may be reduced by reducing meat consumption — and therefore demand — and limiting access to veterinary drugs in low- and middle-income countries’ rural areas. They also suggest that legislative action and subsidies might be used to improve farm hygiene, reducing the need for antimicrobials in general. The authors suggest that high-income countries should support the transition to sustainable animal production in low- and middle-income countries through a global fund that improves biosafety and biosecurity in animal farms; in regions where hotspots are emerging, there is a window of opportunity to stem the growth of antimicrobial resistance through strict hygiene rule in newly built farms.

For many animal advocates, the most obvious solution to these problems would be to greatly reduce or eliminate our consumption of animal products by reducing demand. While advocates work to that end, it may also be worth it for advocates to press governments and agriculture agencies to enact stronger guidelines and restrictions on what’s being used today.