New Methods for Detecting Listeria
McGinnis October 12, 2006
Agricultural Research Service (ARS) scientists in Wyndmoor, Pa., are
improving methods to detect foodborne pathogens like the potentially deadly
Quick, accurate, cost-effective methods for detecting pathogenic
bacteriaessential to ensuring a safe food supplyare part of ARS
food safety research highlighted in the current issue of Agricultural
Listeriosis, the illness caused by L. monocytogenes infection,
affects around 2,500 people in the United States every year, and kills about
500. Newborns, seniors, pregnant women and individuals with compromised or
weakened immune systems are particularly susceptible.
Most methods for detecting harmful foodborne bacteria rely on
antibodies, which are proteins used by the immune system to fight infections
and foreign bodies. Because these antibodies target very specific infections,
researchers can use them to identify and locate specific pathogens.
Antibodies vary in their degree of specificity. Current antibody-based
methods for detecting L. monocytogenes can't distinguish this bacterium
from the mixture of harmless bacteria found in most foods, according to
Tu. He's research leader of the
Biophysics and Residue Chemistry Research Unit at the ARS
Regional Research Center in Wyndmoor.
A molecular method called "phage display" uses bacteria and bacterial
viruses, or phages, to quickly select antibodies to detect pathogens. Now ARS
C. Paoli and chemist
D. Brewster have employed phage display to isolate an antibody fragment
that binds specifically to L. monocytogenes.
The researchers' success demonstrates that antibody phage display can
be used to select antibodies for pathogen detection, even where traditional
methods have proved inadequate.
more about the study and other ARS food safety research in the October 2006
issue of Agricultural Research magazine.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.