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Potato Peel Extract Holds Potential as Antibiotic

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By Alka Agrawal

LOS ANGELES, May 23 (Reuters Health) - An extract made from potato peel

prevents adhesion of bacteria to host cells, which researchers suggest is a

strategy that should be studied as an alternative to traditional

antibiotics.

" Most people interpret anti-infective compounds in the traditional

antimicrobial sense, meaning some kind of chemical that's going to inhibit

the growth or kill bacteria or other microorganisms, " Dr. Marjorie M. Cowan,

of Miami University, in Oxford, Ohio, told Reuters Health. " We were aware

that there were components in plants that instead block the adhesion of

microorganisms to the host tissues. "

Potatoes are widely used medicinally in indigenous cultures, and contain

large amounts of polyphenol oxidase (PPO), she noted. Since PPO is known to

have anti-adhesive properties, her group screened potato extracts and found

that a component of the peel inhibited the adhesion of Streptococcus

sobrinus 6715 and type 1-fimbriated Escherichia coli to their host

receptors, but did not kill the bacteria.

She described her team's findings in a presentation here yesterday at the

annual meeting of the American Society for Microbiology.

Her group suspected that PPO might be responsible for the inhibition,

because the extract had PPO activity, the extract contained a protein that

was the same size as purified PPO, and PPO inhibitors blocked the extract's

ability to block bacterial adhesion. Dr. Cowan said that PPO is known to

work on tyrosines and convert them to quinones, and that 60% of bacterial

binding proteins are known to have a conserved critical tyrosine residue.

However, whether the anti-adhesive action is due to PPO is not really the

issue. " Adhesion is a necessary first step in order to cause disease,

otherwise [bacteria] just get washed out of the body, " she said. " All the

thousands and thousands of people who are screening plants to find

antimicrobial substances, their initial screening techniques would only

catch substances that inhibit growth and would not catch anti-adhesives. "

Researchers working on antiviral strategies already work on blocking viral

attachment to the host, she noted, but blocking adhesion is considered a

novel strategy for antimicrobial compounds.

She noted that antibiotics that kill bacteria can cause release of toxic

substances that can cause damaging inflammatory responses, which would not

be an issue with an anti-adhesive. In addition, she thinks that bacteria

would be less inclined to develop resistance to an anti-adhesive, although

she envisions these compounds as " another weapon in what needs to be a

diverse arsenal of antimicrobial therapies. "

Oxygen-Binding Protein Found in Anaerobic Bacteria May Be Antibiotic Target

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WESTPORT, May 23 (Reuters Health) - A protein that senses oxygen in marine

worms has also been identified in certain bacteria, according to a report in

the May 15th issue of Biochemistry. The finding may point to a new class of

antibacterial agents.

" We weren't looking for this, " Dr. M. Kurtz, Jr., from the University

of Georgia, Athens, told Reuters Health, " it came about by chance. " Dr.

Kurtz and a multicenter team were studying an oxygen-binding protein,

hemerythrin (Hr), found in a few species of marine worms. In searching

protein sequence databases they came across " a sequence that looked like the

same kind of protein except it was in a bacterium, which had never been

found before. "

This oxygen-binding protein was actually a domain in a larger protein in

this bacterium, (DcrH), a chemotaxis protein. " We presumed, " Dr. Kurtz

continued, " that this protein in the bacterium is there to sense oxygen.

That is, it's poisoned by oxygen and so it tends to swim away from oxygen. "

The researchers isolated and characterized the Hr protein and found that it

does bind oxygen, and from databases found it in at least 12 other bacteria.

" It's apparently common. We didn't know that, but as more and more bacterial

genomes are sequenced these proteins seem to come up. "

What we are thinking, " Dr. Kurtz said, " is that maybe this is a general way

that anaerobic bacteria sense oxygen in their environment and are able to

get away from it. " Dr. Kurtz noted that many pathogenic bacteria are

anaerobic, and he believes that it might be possible to develop drugs that

would inactivate this protein.

" The thing that interests me is how this protein developed in the first

place, " Dr. Kuntz said. He noted that originally the earth was an anaerobic

environment, but as oxygen accumulated bacteria either had to adapt or die.

" We think that's when this oxygen-sensing protein developed. It's funny that

it's found in bacteria and not in any organism in between, such as yeast,

and then all of a sudden you find it in these marine worms. The worms don't

need to avoid oxygen so they use it for a different purpose. They adapted

the protein from the bacteria for their own use as an oxygen-storage

reservoir to bind oxygen like we use hemoglobin. "

Diagnosis of Viral Meningitis With EV-PCR Eliminates Unnecessary

Interventions

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By Reinberg

WESTPORT, May 24 (Reuters Health) - Enterovirus polymerase chain reaction

(EV-PCR) testing for aseptic meningitis in children aids clinical

decision-making by avoiding unnecessary diagnostic and therapeutic

interventions and promoting rapid patient discharge, according to a report

from California.

Dr. Mark H. Sawyer from the University of California, La Jolla, and a

multicenter team retrospectively reviewed the medical records of 276

pediatric patients who had undergone a cerebrospinal fluid diagnostic EV-PCR

test in 1998. " This is one of the first studies that really looks at the

impact of new and rapid diagnostic testing on physicians' decision-making, "

Dr. Sawyer told Reuters Health.

As Dr. Sawyer's team reports in the May 24/31 issue of The Journal of the

American Medical Association, 137 patients had a positive cerebrospinal

fluid EV-PCR result. The 95 patients for whom the positive diagnosis was

available prior to discharge had significantly fewer ancillary tests

performed compared with the 92 patients who were EV-negative: 26% versus 72%

had at least one test performed.

The EV-positive group also received intravenous antibiotics for less time

than the EV-negative group, a median of 2.0 days versus 3.5 days, and stayed

in the hospital fewer hours, a median of 42 hours versus 71.5 hours. In

addition, the researchers report that patients who were EV-positive stayed

in the hospital for a median of 5.2 hours after EV-PCR results were

obtained, compared with 27.4 hours for those who were EV-negative.

Dr. Sawyer said that EV-PCR testing " leads physicians to a conclusion more

quickly than they would be able to reach just by clinical observation alone.

It works well in our setting and I would encourage other laboratories to

consider this type of testing, because not only is it useful clinically, but

for the bottom-line people it actually saves money. "

He noted that " in general, because the test comes back so quickly it really

speeds up the process. Physicians can pinpoint infections in hours that in

the past took days or even weeks to diagnose.

JAMA 2000;283:2680-2685.