Livestock are responsible for only a miniscule
percentage of cases of antibiotic resistance in humans and the environment,
according to a new study from Sweden.
People account for almost all the antibiotic
resistance found in a five-year study by Sweden’s National Veterinary Institute.
They analyzed samples of extended spectrum
beta-lactamase (ESBL), a type of enzyme known to confer resistance to
beta-lactam antibiotics, including penicillin and cephalosporins.
The samples were obtained from domestic and imported
foods, farm animals, healthy volunteers, severely ill patients, the environment
and sewage water.
From these 5,300 samples, researchers identified three
separate populations of ESBL: one in Swedish food and farm animals, one in
imported foods and one in humans and the environment.
Six per cent of isolates were ESBLa, which are
attributed to farm animals, while the majority of isolates were ESBLm, which
are found only in humans.
The ESBL genes in the general community population,
sewage water and the environment have an appoximately 90 per cent similarity.
The data also show that animals are associated with a
human infection rate of 0.00022 per cent on a population basis, or 85 people in
a population of 100,000.
Based on these findings, the SVA, together with
Sweden’s Public Health Agency and National Food Agency, concluded that food is
a limited contributor to antibiotic-resistant E. coli infections in humans.
In fact, the potential overlap between clinical human
isolates and isolates from healthy farm animals was found to be extremely
unlikely, according to SVARM 2014, a report responsible for measuring the
consumption of antibiotics and occurance of antibiotic resistance in Sweden.
