Two high-tech tactics may speed identification of Campylobacter
jejuni, the microbe responsible for more cases of foodborne illness in the
United States than any other bacteria. Campylobacter has turned up in
eggs, raw milk, raw or undercooked meat and poultry, raw oysters, and
C. jejuni sickens an estimated 4 million Americans every year. Of
those, some 200 to 1,000 cases are fatal, according to the U.S. Centers for
At the ARS Western Regional Research
Center in Albany, California, scientists have produced two new molecular probes
that seek out and bind to C. jejuni. Known as monoclonal antibodies, the
probes did that job with impressive accuracy in lab tests with about 20
different varieties of bacteria.
The probes might become part of a fast, reliable assay for identifying this
pathogen at the packinghouse, says microbiologist Robert E. Mandrell of the
Food Safety and Health Research Unit at Albany. Or they could be packaged into
a clinical assay to help healthcare professionals identify C. jejuni
when diagnosing cases of gastroenteritisan inflammation of the stomach
What's more, the assay may help in identifying C. jejuni associated
with a nervous system disorder, Guillain-Barré syndrome.C. jejuni
is implicated in as many as 30 to 40 percent of the cases of this disease.
The probes, says Mandrell, may prove less labor intensive and time consuming
than many assays currently used to identify C. jejuni. He developed the
monoclonal antibody probes with colleagues David L. Brandon and Anne H. Bates
at Albany. ARS is seeking a patent.
In related work, researcher William F. Haddon, also in the Food Safety and
Health Unit, is investigating use of a cutting-edge technology known as
MALDI-TOF mass spectrometry to distinguish C. jejuni from other
Campylobacter species and from other microbes as well. There are about a
dozen different species of Campylobacter. Of these, C. jejuni is
the most dangerous to humans.
The sophisticated instrument that Haddon and co-researchers Bates, Mandrell,
Leslie A. Harden, and Marian R. Wachtel use for this approach emits a laser
beam to zap pathogen samples. When the beam strikes the sample, proteins break
away from it.
Teamed with a computer, the instrument can determine the weightor
massof different proteins, measured in units known as daltons. The
result: a distinctive fingerprint, or profile, of the array of proteins from
the zapped sample. The profile, displayed as an easy-to-read graph generated by
the computer, may reveal the identity of the microbe.
That's what happened in preliminary tests of four different
Campylobacter species. A protein weighing 13,724 daltons, for instance,
was detected from the C. jejuni specimen. But it didn't show up in
analyses of the C. fecalis, C. coli, or C. jejuni
Key to this approach: the instrument's precision. It can calculate protein
weight to within 5 daltons.
Besides precision, the technique also offers the promise of speed: once a
sample is prepared for analysis, results can be ready in about 3 minutes. With
further work, this technology may yield one of the fastest and easiest ways to
correctly identify foodborne pathogens. By
Marcia Wood, Agricultural
Research Service Information Staff.
This research is part of Food Safety, an ARS National Program described on
the World Wide Web at http://www.
Scientists named in this article are in the USDA-ARS
Food Safety and
Health Research Unit
, Western Regional Research Center, 800 Buchanan St.,
Albany, CA 94710; phone (510) 559-5610, fax (510) 559-5948, e-mail
for Campylobacter" was published in the
March 1999 issue of Agricultural