Image credit: Zhou, et al. ©2010 American Chemical Society.
Warmer weather and the summer season will soon be upon us. For many extended time outdoors has the potential to produce more cuts and bruises and ultimately the need for more band-aids. Although not ready yet, the band-aids of the future may be smarter and more effective at stopping infection if research by a group in England is successful.
Dr. Toby Jenkins and his colleagues at the University of Bath in England have pioneered a new type of dressing for wounds. His engineered fabric contains small capsule-like vesicles containing antibiotics. While this may not seem remarkable or different from some of the products on the market, what is different is the way in which bacteria “see” these vesicles. The vesicles appear to bacteria like human cells that are prime targets for infection. As a result, bacteria attack the vesicles, bursting them. The burst releases the antibiotic, which then kills the infecting bacteria and any similar bacteria nearby. What’s even more amazing is that his preliminary research has shown that the vesicles are only burst by pathogenic but not by non-pathogenic bacteria. This means that the fabric can be selective in its targets, a major plus when treating wounds on the human body, an area that is covered and filled with many non-pathogenic and even beneficial bacteria.
So how exactly does this fabric work and how can it be selective? One of the keys to this fabric lies in its ability to select pathogenic bacteria. Pathogenic bacteria are generally defined as those bacteria that cause disease. Examples of pathogenic bacteria include Staphylococcus aureas (pneumonia, toxic shock syndrome), Clostridium botulinum (botulism), and Streptococcus pyogenes (strep throat). Examples of non-pathogenic bacteria include certain strains of E.coli which are found in human intestines, Staphylococcus epidermis found as a normal part of human skin, and Lactobacillus acidophilus, a normal part of our intestines.
Structurally and chemically there are differences between pathogenic and non-pathogenic bacteria. Many of these differences account for why pathogenic bacteria can invade the body and destroy human cells and tissues. Two of the differences between pathogenic and non-pathogenic bacteria are invasiveness and toxigenesis. In other words, pathogenic bacteria can invade and overcome host defenses (invasiveness) and can produce toxins (toxigenesis). Toxins are lipids and proteins that can cause damage to cells and tissues through a variety of mechanisms. Some toxins are specific such as botulinum neurotoxin, which attacks nerve cells and stops them from firing. Other toxins are more broad in their actions and simply lyse (break apart) cells or travel through the blood stream and cause effects such as inflammation or inhibition the synthesis of proteins in cells. Non-pathogenic bacteria are generally defined as those that do not invade tissue or produce toxins.
The idea behind the vesicles on the wound fabric is that they burst as a result of the toxins produced by pathogenic bacteria but remain intact around non-pathogenic bacteria since these bacteria do not produce toxins. Jenkins and colleagues tested their design by using two types of pathogenic bacteria: Staphylococcus aureas and Pseudomonas aeruginosa and one type of non-pathogenic bacteria: a certain strain of E.coli. They placed the wound fabric in petri dishes along with each type of bacteria and took samples of the bacteria populations every 20 minutes for 4 hours. Over that period they found steady decreases in the concentration of the two pathogenic bacteria, Staphylococcus aureas and Pseudomonas aeruginosa, to the point of almost complete inhibition of growth. In contrast they found almost no reduction in the growth of the E.coli. The very minimal reduction in E.coli growth was attributed to some leaking from the vesicles themselves. They suggest that these results show the ability of the vesicle-coated fabric to select pathogenic versus non-pathogenic bacteria. Jenkins and his group are quick to point out that this was a preliminary test and that more research and work needs to be done in order for this type of product to find its ways to hospitals. One of the next steps is to expand the testing to include many, many more types of bacteria. Others in the field agree, suggesting that for use in hospitals, a discrimination based only on the ability to produce toxins may not be as effective as other specific criteria.
However, most scientists in the field see this preliminary work as a step in the right direction, particularly since the medical field is facing a new era of antibiotic resistance. Many theorize that this type of “smart” wound fabric would help to curb the rapid pace of antibiotic resistance since the antibiotic would only be released if pathogenic bacteria are “on site.” This mechanism would reduce what scientists term “the selection pressure” on bacteria that helps drive the evolution of resistance to antibiotics.
For LabLearner students the research in this article emphasizes some of the major concepts they encounter in CELLs and GAP Units such as Cellular Organization, Genes and Proteins, Properties of Matter, Chemical Reactions, Adaptation, Classification. These concepts include an understanding of cellular membranes, organism and cellular reproduction, specificity of chemical reactions and selection, evolution and adaptation. In addition it highlights the combination of problem solving and experimental design that students experience in LabLearner Labs and Performance Assessments. And who knows where this research and research by LabLearner students will take us. The next time you’re looking for band-aids, you might find the answer.
If you’re interested in learning more about bacterial pathogenesis or the evolution of antibiotic resistance check out these links:
The Microbial World: Bacterial Resistance to Antibiotics
The Microbial World: The Mechanisms of Bacterial Pathogenicity
An interesting post right there mate . Thank you for it !