For the past six years Dr BR Shome, a scientist with the National Institute of Veterinary Epidemiology and Disease Informatics in Bengaluru, has been testing milk samples to check for drug-resistant microbes. With antibiotic resistance becoming one of the biggest health crises around the world and in India, Shome is one of a handful of researchers in the country checking on how drug-resistant microbes may be passed on to people through food.
Shome has found that the presence of methicillin-resistant Staphylococcus aureus in milk from Kolkata, Kochi, Bengaluru, Assam and Haryana is below five percent. Methicillin-resistant Staphylococcus aureus is a bacterium that is resistant to most antibiotics and can cause anything from skin infections to the possibly fatal sepsis and pneumonia. Shome and his colleagues have also checked milk for enzymes called extended-spectrum-beta-lactamases produced by bacteria such as Escherichia coli, which are also resistant to many antibiotics. They found that about 15% of the samples had the presence of the enzyme.
“The data shows that drug-resistant bacteria in the milk is strikingly low as compared to levels in humans,” said Shome. However, even though the preliminary findings are not worrying, Shome and other Indian researchers are continuing to look for drug-resistant microbes in milk and other food sourced from animals.
India is one of five countries that are the largest consumers of antibiotic through food sourced from animals, according to 2015 report from the Organisation for Economic Co-operation and Development. Other countries with high levels of antibiotic consumption through food are China, the United States, Brazil and Germany. In 2010, global antibiotic consumption from livestock sources was estimated at 63,200 tons.
For more than a decade, researchers have been studying antibiotic resistance of microbes among people in India. They have been conducting surveillance in hospitals for hospital-acquired infections. But, there has been very little work on burgeoning drug-resistance on farms and in fisheries.
Drug-resistant pathogens can be transferred from animals to humans through food causing the spread of antibiotic resistance that can trigger cascades of drug failures and deaths by diseases that have been preventable so far.
Researchers in India are, therefore, turning their attention to this largely ignored field. “The surveillance data is crude, as there are very few centres involved in the research,” said Shome.
Identifying the problem
In 2011, when Shome wanted to study antimicrobial resistance among cattle, he tried to get funding from Indian institutions and from abroad. He was studying the various pathogens that cause mastitis, an infection in the cow’s udders that affects milk production. For three years he got no funding.
In March this year, officials from the Food and Agriculture Organisation in collaboration with the Indian Council of Agriculture Research and the Indian Council of Medical Research identified 25 research areas in the veterinary sector for antimicrobial research. These included research on the extent of antimicrobial use in the different sectors, the extent and patterns of antimicrobial resistance in different sectors, and the identification of pathogens that have resistance.
On April 19, policy makers decided to adopt a holistic approach to tackling and controlling antimicrobial resistance. Former Environment Minister Anil Dave, Minister of Consumer Affairs Ram Vilas Paswan and officials from the ministry of AYUSH and the department of animal husbandry signed what was called the Delhi Declaration on Antimicrobial Resistance. The declaration pledged to adopt a holistic and collaborative approach towards prevention and containment of antimicrobial resistance in the country.
“Our understanding about the industry and its role in antibiotic resistance is minimal,” said Dr Rajesh Bhatia, regional technical advisor for the FAO. “But what we do know as a fact of life is that more the consumption of antibiotics, more the resistance. We are all working on that presumption.”
The new interest in this critical field of health research has helped Shome get funding from the FAO and support from the Indian government.
For more than 10 years now, public health organisations such as World Organisation for Animal Health and the FAO have been talking about promoting “one health”. The idea introduced by World Organisation for Animal Health stems from the fact that human health and animal health are interdependent and bound to the health of ecosystems in which they exist.
Addressing antimicrobial resistance requires a holistic and multisectoral approach, which needs to involve people dealing with animal health since antimicrobial resistance does not recognise geographic or human-animal borders.
Like in humans, antibiotics are given to animals treat their infections. “Often animals are given antibiotics without investigating the cause of infection,” said Dr Jyoti Misri of the Indian Council of Agricultural Research.
But antibiotics are also given to entire flocks or herds of animals as a prophylactic, a measure to prevent infection from sweeping through the animal population. Antibiotics are also used as growth promoters in animals.
“The use of antibiotics as growth promoters is used to increase the weight of the animal and therefore related to economics of production,” said Misri.
About 60% of human infections are of animal origin and antimicrobial resistance can be passed to humans through food and to people who have direct contact with animals like farmers and animal handlers. These pathogens can also spread to people who are handling of raw meat before cooking. The microbes can also be passed through ingestion of water contaminated by stools or urine in water.
Sometimes, resistant microbes may not jump from an animal to a person but there might be a transfer of genetic elements between microbes common to animals and humans. Such transfers allow drug-resistant properties or determinants in the animal pathogen to be transferred to the human pathogen.
Need India-specific studies
There has been very little research on drug resistance of microbes among animals or the presence of antibiotics in animal meat. A 2015 report by the think tank Centre for Disease Dynamics and Economic Policy refers to studies that have found bacteria with 100% resistance to the antibiotic sulfadiazine among chickens and other fowl. Researchers have also found widespread bacterial resistance to amikacin, carbenicillin, erythromycin, penicillin, and streptomycin.
Currently, the FAO is helping the Indian Council of Agricultural Research acquire standards for measuring antimicrobial resistance in animals.
“There are different breakpoints to declare pathogen resistance in humans and animals, because their dosages are different,” said Dr Kamini Walia who is coordinating the animal research on drug resistance for the Indian Council of Medical Research. A breakpoint is a concentration of an antibiotic that defines whether a pathogen is are susceptible or resistant to it.
These standards are being adopted in India for the first time in new surveillance programmes for livestock, poultry and fisheries. India also needs to test the effect of antibiotics as growth promoters among livestock and whether they actually help increase the weight of animals and so their meat content, said Bhatia.
The Indian Council of Medical Research and the Indian Council of Agriculture Research are meeting to discuss which antibiotics need to be restricted or banned completely for use in animals. For instance, colistin is a drug of last resort that is prescribed to patients when all other antibiotics have failed but is currently used extensively to prevent infections in animals. Colistin resistance, if passed from animals to humans, can be calamitous.
“We need to tell farmers not to use last resort antibiotics because ultimately everyone will suffer,” said Bhatia.
Even though the Food Safety and Standards Authority of India has banned the use of antibiotics in fisheries, there is no such regulation for the poultry and livestock industries.
Even with the severity of the problem, Bhatia feels that a blanket ban on the use of antibiotics in animal husbandry may not be effective. The government will have to bring farmers into the conversation and the process of cutting down on indiscriminate antibiotic use.
“If there is no qualified veterinarian or laboratory in a village, we cannot stop a farmer from feeding his cattle or poultry antibiotics,” said Bhatia. “We need to provide them with alternatives.”