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| A New Bacterium | |
In 1986, a
Georgia Tech biology
professor in collaboration
with scientists at the Centers for Disease Control (CDC)
confirmed and reported the first cases of human gastrointestinal
illness associated with a bacterium they had first identified
only two years earlier in pigs with gastrointestinal illness.
The bacterium, Campylobacter hyointestinalis, is a distinct
species in the genus Campylobacter. One other species in this
genus (C. jejuni) is responsible for an estimated two million
cases of diarrheal illness in people in the United States every
year. C. hyointestinalis is one of the least common species of
the genus, but it caused severe illness in the four patients in
which it was reported in the Journal of Clinical Microbiology in
1987.
Researchers, led by Georgia Tech's Dr. Paul Edmonds,
isolated the bacterium from the patients' stool specimens. They
used the DNA-DNA hybridization technique to genetically confirm
the identification of the strains. The technique, developed at
the CDC, continues to be a state-of-the-art method for
identifying unknown strains of bacteria based on a high degree of
matching gene sequences in the DNA from samples examined.
The authors also reported that, like patients with illnesses
caused by other species in the Campylobacter genus, patients with
C. hyointestinalis infections responded well to treatment with
the antibiotic erythromycin.
The researchers noted that all four patients in this study
could be considered as having compromised health: One was an
elderly woman who had recently traveled in Egypt; two were
homosexual men; and the fourth was an infant who had been
drinking raw milk and untreated well water.
Shortly after the
study ended, the researchers received two additional stool
specimens containing C. hyointestinalis. These were from an
elderly man and a 3-year-old boy. Researchers suggested that
further research needed to confirm whether the bacterium is
restricted to presumably compromised patients or whether it can
infect otherwise healthy people.
The researchers' findings were published in the April 1987
issue of the Journal of Clinical Microbiology. Edmonds was the
lead author. Since the publication of the article, other
researchers have reported at least six more cases of human
gastrointestinal disease associated with C. hyointestinalis. At
least one of those cases was in a patient whose immune system was
compromised by leukemia. The CDC does not compile statistics on
disease related to this bacterium.
Also, since publication of the Edmonds, et al. article, C.
hyointestinalis has been reported in cattle, sheep, mussels,
oysters, Macaca nemestrina monkeys and Moluccan rusa deer. A new
subspecies has been identified in pigs.
Another more recently developed hybridization technique for
identifying bacterial strains is based on 16S rRNA sequence
analysis. But the technique called polymerase chain reaction
(PCR) is now the most efficient method of detecting the presence
of C. hyointestinalis in clinical specimens.
Courtesy of Dr. Paul Edmonds
The bacterium, Campylobacter hyointestinalis, was first
identified in humans in 1986 by Georgia Tech biology professor
Dr. Paul Edmonds. Though rare, it causes severe intestinal
illness in humans.
For more information, contact Dr. Paul Edmonds,
School of Biology,
Georgia Tech, Atlanta, GA 30332-0230. (Telephone: 404-894-3737) (E-mail:
paul.edmonds@biology.gatech.edu)
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