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Beyond the antibiotic frontier

For many people in the food industry, lactic acid bacteria are organisms used in the fermentation process, but these bacteria have so much more to offer the world. Professor Leon Dicks of the department of microbiology at the University of Stellenbosch studies lactic acid bacteria and has discovered­ innovative ways to use them. A new-age antimicrobial and a vastly improved probiotic are just two examples.

Although the antimicrobial and preservative properties of lactic acid bacteria have been known for a while, Dicks and his team are among the first in the world to use these bacteria to fight infections in both humans and animals.

"We screened close to 600 strains looking for unique antimicrobial peptides," says Dicks. Antimicrobial peptides (AMPs) are protein structures produced by the lactic acid bacteria that have antimicrobial properties. He found two strains that produce broad-spectrum AMPs that are highly effective against pathogens (micro-organisms that cause disease).

Testing against some of the best-known antibiotics on the market showed that the unique AMPs performed as well, if not better in some cases.

Antibiotics have been a mainstay against infections for decades but pathogens are becoming increasingly resistant to them. The Staphylococcus aureus infection is a case in point, with up to 95% of the strains being resistant to penicillin and 70% to methicillin (and thus called MRSA – methicillin-resistant S aureus).

These days we also get VRSA, vancomycin-resistant S aureus, and vancomycin is seen as a "last-resort" antibiotic. It's time for an alternative to antibiotics and Dicks' two AMPs fit the bill.

They work in a completely different­ way to traditional anti­biotics. Whereas pathogens have mutated to prevent antibiotics from entering their cell walls, thus developing resistance, the AMPs work like a bullet and leave a large hole in the cell wall, from which the pathogens cannot recover.

Dicks and his team have developed a patented nanofibre wound dressing with these unique AMPs. "The dressing matrix provides control over the concentration and release of the two AMPs," says Dicks.

Nanofibres are so small they can only be seen under an electron microscope. The nanofibres are spun rapidly and are impregnated with the two AMPs to form a tissue-like dressing. "Our trials have shown that the nanofibre dressing effectively kills Staphylococcus aureus," says Dicks.

Two types of dressing have been created. One is biodegradable and acts as a support matrix for skin as it heals. "This is particularly important with burn wounds as you do not need to replace the dressing, causing less patient distress," says Dicks. The other nanofibre dressing is nonbiodegradable and is taken off once a week. The products will be distributed worldwide.

Most of the equipment needed for the research into lactic acid bacteria had to be created in-house at the university and new methods and protocols had to be developed for the experiments on nanofibre dressing. "Funding from CiplaMedpro was instrumental [in this]," says Dicks.

Dicks' research has also led to the discovery of novel probiotic strains.

Dicks has seven patents, with several­ more pending. He has supervised 36 Masters and PhD students and is currently the only scientist in South Africa who heads a research team that focuses only on lactic acid bacteria, their antimicrobial peptides and probiotic strains.

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