Science - May 30, 2013

Resistant bacteria spare locals

Link between ESBL in animals and people remains a mystery.

The risk of contracting antibiotic-resistant ESBL infections is no higher for residents in areas with many chicken farms, according to the results of PhD researcher Patricia Huijbers. She tested 1025 residents of different municipalities to see whether they were carrying the ESBL bacterium. Some of the test subjects lived in an area with a lot of poultry farms, others in areas with few chickens. On average, 5.1 percent of the residents were carriers of the ESBL bacterium. There were no more carriers among residents of municipalities with many chickens than those in areas with few chickens.
This finding means the role of farm animals in spreading the resistant ESBL bacterium remains a riddle. ESBL bacteria are present on 100 percent of the chicken farms, 40 percent of pig farms and half of all calf farms, but there is no direct link between the resistant bacteria in humans and in animals. One third of poultry farmers do, however, carry ESBL, sometimes with the same ESBL genes as are found in their chickens. It is not clear, then, how the transfer between animals and humans takes place. Contact with veterinary doctors might play a role, suggest Huijbers in her article in Clinical Microbiology and Infection.