Researchers at the Johns Hopkins Bloomberg School of
Public Health have found evidence of a
novel pathway for potential human exposure to
antibiotic-resistant bacteria from intensively raised
poultry: driving behind trucks transporting broiler
chickens from farm to slaughterhouse.
A study by the researchers found increased levels of
pathogenic bacteria, both susceptible and
drug-resistant, on surfaces and in the air inside cars
traveling behind trucks that carry broiler
chickens. The study is the first to look at exposure to
antibiotic-resistant bacteria from the
transportation of poultry. The findings are published in
the first issue of the Journal of Infection and
Public Health.
Typically, broiler chickens are transported in open
crates on the back of flatbed trucks with no
effective barrier to prevent release of pathogens into the
environment. Previous studies have
reported that these crates become contaminated with feces
and bacteria.
The study was conducted on the Delmarva Peninsula, a
coastal region shared by Maryland,
Delaware and Virginia that has one of the highest densities
of broiler chickens per acre in the United
States. Ana M. Rule, a research associate in the Bloomberg
School's Department
of Environmental Health Sciences, along with Professor
Ellen K. Silbergeld and Sean L. Evans collected air and
surface samples from cars driving two to three car lengths
behind the poultry trucks for a distance of 17
miles. The cars were driven with air conditioners and fans
turned off and with the windows fully
opened. Air samples collected inside the cars showed
increased concentrations of bacteria (including
antibiotic-resistant strains) that could be inhaled. The
bacteria were also found on a soda can inside
the car and on the outside door handle, where they could be
touched.
"We were expecting to find some antibiotic-resistant
organisms, since it's pretty clear that the
transportation conditions for these chickens are not closed
or contained," Rule said. "Our study shows
that there is a real exposure potential, especially during
the summer months, when people are driving
with the windows down; the summer is also a time of very
heavy traffic in Delmarva by vacationers."
The strains of bacteria collected were found to be
resistant to three antimicrobial drugs widely
used to treat bacterial infections in people. These drugs
are approved by the U.S. Food and Drug
Administration for use as feed additives for broiler
poultry. The study findings were consistent with
other studies on antibiotic resistance in poultry flocks
and poultry products.
According to the authors, the findings support the
need for further exposure characterization
and attention to improving methods of biosecurity in
poultry production, especially for regions of high-
density farming such as the Delmarva Peninsula.
Support for the study came via the
Johns Hopkins Center
for a Livable Future's Innovation
Grant Program.