Published on March 14th, 2011 | by Rachel Shulman1
Scientists Combat Meat Industry’s Dismissal of Antibiotic Resistance
In addition to spawning epidemics of zoonotic diseases such as bird flu that can “jump” from livestock to humans, industrial farms are contributing to an outbreak of ‘superbugs’ – bacteria that are resistant to antibiotics.
People can become infected with superbugs by working in close proximity to the animals themselves or by eating tainted meat. A recent study shows that people can even be infected via insects that transport antibiotic resistant bacteria from factory farms to surrounding residential areas.
When superbugs infiltrate hospitals, they can make sick people even sicker. One well known example is Staphylococcus aureus, or MRSA, a multi-drug resistant species that kills 20,000 Americans every year.
Although there’s an extensive amount of evidence showing that giving antibiotics to animals spreads antibiotic-resistant bacteria to people, the meat industry has refused to accept that excessive antibiotic use in agriculture is to blame for the dramatic increase in antibiotic resistance.
The meat industry argues that the rise of superbugs might be attributable to increased antibiotic use outside agriculture – such as use in human medicine.
But recent research is working to combat that argument.
A new study shows that chickens, chicken meat, and humans are carrying identical, highly drug-resistant E. coli. The research suggests that antibiotic resistance is being spread through the food chain.
The researchers collected samples of E. coli, a common gut bug, from live poultry and retail chicken meat. They looked for a particular resistance pattern: extended-spectrum beta-lactamase resistance, or ESBL.
ESBL is an emerging problem in human medicine. It tends to appear in species of bacteria such as E. coli that cause hospital-acquired infections in vulnerable people such as ICU and burn patients. ESBL is resistant to whole families of drugs, which means big trouble for patients who are already at risk.
ESBL incidence has been rising over the past two decades. It’s even been increasing in the European Union (EU), where, unlike in the US, human antibiotic use is strictly controlled by the government in an effort to decrease the selective pressure that drives the evolution of resistant bacteria.
So scientists recently started to investigate whether antibiotic use in livestock is spawning ESBL resistance in the EU. They found that, in the Netherlands – a country with conservative human antibiotic use but the most liberal agricultural antibiotic use of any EU member – the percentage of ESBL-containing E. coli in chickens increased five-fold between 2003 and 2008.
In the new study, researchers also looked for ESBL-containing E. coli in chicken meat. They found that 92 of 98 chicken meat samples contained ESBL.
The researchers then analyzed a national database of drug-resistant bacteria in humans. They found that a significant number of human incidences of ESBL-containing E. coli were genetically indistinguishable from those obtained from poultry samples and chicken meat, which suggests that drug-resistance is being transferred from farms to humans via food.
This study is just one more on a long list of studies showing that overuse of antibiotics on factory farms is a threat to human health. Let’s hope that the meat industry starts to accept the facts!