Multidrug-resistant Bacteria Found in Chickens in India

A study of 100 chickens collected from a marketplace in India finds multidrug-resistance in an emerging bacterial pathogen, and has researchers calling for improved food safety, monitoring, and surveillance.

New diseases are constantly emerging and animals are one of the biggest sources of pathogens. In a recent study, a team of researchers in India discovered multidrug-resistant genes in bacterial samples collected from poultry chickens.

According to the Centers for Disease Control and Prevention (CDC), tens of thousands of people in the United States contract zoonotic diseases each year from contagious pathogens spread between animals and humans. Some of these common and dangerous diseases include Lyme disease, West Nile virus, malaria, Salmonella and Escherichia coli (E. coli) infections, which are spread through tick bites, mosquito bites, or contact with farm or wild animals. More than 6 out of the 10 known infectious diseases that individuals acquire come from animals, according to the CDC. Bacterial food-borne zoonoses infect millions of individuals each year, according to the World Health Organization (WHO), but these public health threats have not been priorities for public health agencies as the impact of these diseases hits hardest in poor communities in rural developing countries, which makes them hard to eradicate.

One such animal-borne bacterial pathogen is Helicobacter pullorum, which can lead to gastroenteritis, or stomach flu, in humans. These bacteria can get into the gut and lead to an infection, causing abdominal cramping, pain, nausea, vomiting, and bloody stool. H. pullorum bacteria are most often transmitted through contaminated meat, poultry, water, or through unhygienic food handling. Previous studies have found that these bacteria are often found in chickens, turkeys, and other fowl, and although they are less prevalent in humans, H. pullorum is considered an emerging zoonotic human pathogen.

A group of researchers from the University of Hyderabad in India and the Robert Koch Institute in Germany recently studied H. pullorum isolates found in chickens from commercial retail poultry operations in India. The study was recently appeared in Applied and Environmental Microbiology, a journal published by the American Society for Microbiology. The researchers aimed to examine how high antibiotic use by those raising poultry and the subsequent prevalence of multidrug-resistant (MDR) bacteria creates potential risks to human health.

In their investigation, the researchers collected samples from the gastrointestinal tracts of 55 broiler chickens and 45 free range chickens in India, where annual consumption of poultry meat is rising by about 12% each year. In India and other such developing countries, the issue of antimicrobial resistance (AMR) is exacerbated by high population density, poor sanitation, and more lenient antibiotic policies, according to the study authors.

“We targeted wet market poultry outlets for our sampling, keeping in mind that poultry in India are often fed with antibiotics to promote weight gain,” said author Niyaz Ahmed, PhD, of his team’s focus in a recent press release. “These practices most likely boost spread of drug-resistant pathogens among animals and humans, posing a significant public health risk.”

From the samples they collected, the researchers sequenced the genomes of 11 H. pullorum isolates, finding that each one carried five or six known antibiotic-resistant genes that make pathogens unsusceptible to fluoroquinolones, cephalosporins, sulfonamides, macrolide antibiotics, and others. In addition, the isolates showed the ability to produce enzymes called extended spectrum β-lactamases, which imparts resistance to penicillin antibiotics. While cases of human disease caused by H. pullorum have not been widespread, these findings shed light on the bacteria considered to be an emerging pathogen.

“Our study suggests that chickens could be a major source for transmission of emerging MDR pathogen, H. pullorum, from poultry to humans,” concluded the authors. “Given that India has the world’s fifth largest poultry industry and a large consumer base of approximately 500 million customers for chicken meat, food-associated acquisition of AMR and MDR genes, virulence genotypes and phenotypes represents an alarming situation and our study constitutes a baseline, pioneering effort at dissecting this situation from pathogen biology and epidemiology point of view.”