Poultry workers in the United States are 32 times more
likely to carry E. coli bacteria resistant
to the commonly used antibiotic gentamicin than others
outside the poultry industry, according to a
recent study conducted by researchers at the Johns Hopkins
Bloomberg School of Public Health.
While drug-resistant bacteria, such as E. coli,
are common in the industrial broiler chicken
environment, this is the first U.S. research to show
exposure occurring at a high level among industrial
poultry workers. The results are published in the December
edition of Environmental Health
"The use of antimicrobials in industrial food
production has been going on for over 50 years in
the United States," said the study's lead author, Lance B.
Price, who serves on the research faculty of
the Johns Hopkins School of Medicine's Division of Infectious
Diseases and is a scientific adviser to
the School of Public Health's Center for a Livable
Future. "Some estimates indicate that well over half
of the antimicrobial drugs produced in the United States
are used in food animal production. In the
U.S. alone, over 9 billion food animals are produced
The study was conducted with poultry workers and
community residents in the Eastern Shore
regions of Maryland and Virginia, and it confirms similar
studies in Europe showing that poultry
farmers and workers are at risk of exposure to
drug-resistant E. coli bacteria. The Maryland and
Virginia regions on the Delmarva Peninsula are among the
top broiler chicken–producing regions in the
United States, producing more than 600 million chickens
In the study, researchers conducted in-depth analyses
of 49 study participants, 16 working
within the poultry industry and 33 community residents.
Stool samples from the participants were
tested for resistance to the antimicrobials ampicillin,
ciprofloxacin, ceftriazone, gentamicin and
tetracycline. Findings showed that poultry workers had 32
times greater odds of being colonized with
gentamicin-resistant E. coli than other members of
the community. "One of the major implications of
this study is to underscore the importance of the
nonhospital environment in the origin of drug-
resistant infections," said Ellen K. Silbergeld, senior
author of the study.
Price and other researchers note that as food animal
production shifted from the independent
farmer to large-scale industrialized operations, the use of
antimicrobials in feeds intended to
stimulate growth has increased. Currently 16 different
antimicrobial drugs are approved for use in
U.S. poultry production, with gentamicin reported to be the
most widely used.
Additional study authors are Jay P. Graham, Lelia G.
Lackey, Amira Roess and Rocio Vailes, all of
the Bloomberg School.
The majority of this research was supported with
grants from the Center for a Livable Future.