Not just animal meat but plant-based foods are also serving as vehicles for transmitting antibiotic-resistant bacteria to the gut microbiome of humans, warn researchers.
The US Centers for Disease Control and Prevention estimated that of the two million antibiotic-resistant infections per year in the country, 20 per cent are linked to agriculture.
This estimate is based on patients who directly acquire antibiotic-resistant superbugs from eating meat.
"Our findings highlight the importance of tackling food-borne antibiotic-resistance from a complete food chain perspective that includes plant-foods in addition to meat," said Marlene Maeusli from Keck School of Medicine at the University of Southern California.
To reach this conclusion, the researchers developed a novel, lettuce-mouse model system that does not cause immediate illness to mimic the consumption of superbugs with plant-foods.
They grew lettuce, exposed it to antibiotic-resistant E. coli, fed it to the mice and analyzed their faecal samples over time.
"We found differences in the ability of bacteria to silently colonize the gut after ingestion, depending on a variety of host and bacterial factors," said Maeusli.
"We mimicked antibiotic and antacid treatments, as both could affect the ability of superbugs to survive the passage from the stomach to the intestines."
Little has been done till date to determine how eating plants contributes to the spread of antibiotic-resistant superbugs.
Spread of antibiotic-resistant superbugs from plants to humans is different from outbreaks of diarrheal illnesses caused immediately after eating contaminated vegetables.
Superbugs can asymptomatically hide in or "colonize" the intestines for months or even years, when they then escape the intestine and cause an infection, such as a urinary infection.
"We continue to seek the plant characteristics and host factors that result in key microbial community shifts in the gut that put us at risk for colonization and those that prevent it," said the researchers at the meeting of the American Society for Microbiology.