Athlete's Foot Treatment Proposed for Red Tides

June 13, 2008 -- Two agents used to treat athlete's foot may also help battle harmful algal blooms, which can be toxic to fish and shellfish, and potentially lethal to humans.

In laboratory experiments, Takuji Nakashima of the National Institute of Technology and Evaluation in Kisarazu, Japan and colleagues found that two antifungal agents were both effective at killing two types of algae that cause harmful algal blooms, commonly called red tides.

These blooms come in many varieties caused by different algae. The two that Nakashima tested are known to kill fish and shellfish.

"Our results suggested that antifungal agents are effective against the growth of red tides by interfering with the ergosterol biosynthetic pathway in the plankton cells," Nakashima said.

Ergosterol is part of the cell membrane in fungi, and Nakashima's new findings suggest it also is critical to the algae studied.

In earlier work, Nakashima discovered a marine bacterium that produced a compound effective against both fungi and harmful algae. Having discovered this crossover activity, Nakashima turned his attention to the conventional chemical antifungal compounds, bifonazole and terbinafine hydrochloride, both used in athlete's foot preparations.

It may be possible to treat local blooms identified by satellite or other methods, by delivering the compounds by boat, Nakashima said. The compounds are safe for humans but, he noted, "it is necessary to examine the impact of antifungals on environment."

This is a crucial step, agreed Jan Landsberg of the Florida Fish and Wildlife Conservation Commission, who studies harmful algal blooms. Others have proposed similar methods for killing off blooms using antibacterial or antimicrobial compounds, she said.

"With a lot of these, there's a really long way to go from saying, 'This is what happened in the laboratory' to what will happen in the field," she said, adding, "If you apply this particular fix, is it going to create more ecological problems?"

Antifungals could be useful in certain situations, she said.

"You might be able to do something in the short-term for a day or two just to remove a very acute situation," like a bloom encroaching on fish in net pens for aquaculture.

In general, however, she'd rather see efforts focused on preventing the tides from occurring in damaging locations in the first place.

Agricultural runoff or sewage may put nutrients in the water that feed the blooms in coastal areas, where they pose the most harm to humans and seafood, she said. This may contribute to when and where the blooms develop and stay.

"I think most of us are favoring trying to get there at the beginning and trying to figure out why the bloom is happening in the first place and what's keeping it going," she said.

Related Links:

Jessica Marshall's blog: EnvironMental Case

Discovery Tech Blog: EasTech

How Stuff Works: Red Tide

Planet Green

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