Researcher Finds Way To Kill Bacteria In Tiny Places

While talking with a colleague from the LSU School of Dentistry, the Ag Center's Dr. Donal Day realized that the problems he was facing in sugar mills are similar to those found in dentists' offices.

So working with Dr. John Mayo in the dental school's Department of Microbiology, Immunology, and Parasitology, Day began investigating how to control bacteria in tight spaces.

Because it is water driven, modern dental equipment provides an environment where bacteria can thrive.

"There are little or no effective methods for cleaning dental equipment inside," Day explains. "The tubes are very narrow. They're plastic, so they can't take the heat to be sterilized in an autoclave. And there's been no real chemical remedy to attack the films."

The process developed by Day and his colleagues stemmed from his work with dextran, a chain of simple sugars formed by microorganisms that causes sanitation problems in sugar processing systems.

"Most bacteria are controlled by simple cleaning," Day says. "But occasionally there are places where normal cleaning is difficult.

"Some bacteria tend to grow on surfaces and protect themselves by building a slime layer -- a biofilm -- that helps them stick to the surfaces and protects them from penetration by outside elements," he adds. "Dextran is a result of one made by some of these bacteria."

Although these thin layers of microorganisms can show up on almost any surface, they're particularly a problem in concealed places like the insides of pipes and tubes. It's difficult to get inside and scrub the surfaces, Day says, and flowing liquids slide right over the slime layers.

"Although bacteria can grow in any environment, they do better in static water than in flowing water, so down time on the dental equipment causes increased problems," Day says.

Day and his colleagues, including former student Dr. Mark Ott and current graduate student Duwoon Kim, developed a combination of chemicals that first strip the biofilm from the bacteria and then kill them with disinfectant.

In dental equipment, the solution is injected into the water system at the end of the day and then flushed out the following morning. The results, Day says, are powerful.

"It's effective against organisms in films where normal cleaning isn't effective," he says. "It's rapid and works within one minute."

Day explains that pathogens that produce biofilms can be more virulent because normal remedies don't work on them. "The film is a defensive mechanism," he says.

Although the patented process was first used with dental equipment and has a bright future in those applications, Day says the chemicals can be put to a wide variety of uses.

The microbiologist explains that the chemical combination can be put in a spray bottle and used to clean most any surface.

"The uses are expanding beyond dental equipment," he says. "The next application may be poultry processing."