Our natural products: Effective against nasty biofilm forming bugs

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Biofilm is in fact a home of microbial community but highly detrimental against human health. If we look around in our life, at first glance, it is not really clear what dental plaque is the persistent slime in your shower drain-out and ultimately converted into slippery submerged rock. They are actually hibernating home of microbes, even the deadly pathogens. The biofilm in fact is a virulence factor of a bug that enhances its power to cause serious infection. According to microbiologists, even antibiotic cannot easily penetrate into the biofilm tough coating and hence these bugs love to live together and enjoy and injure human beings. They can be responsible for a very huge variety of life threatening chronic diseases.

In most natural environments, association with a surface i.e biofilms, truly the prevailing microbial lifestyle. Sur-face association is an efficient means of lingering in a favorable microenvironment rather than being swept away by current. It is clear that microorganisms undergo profound changes during their transition from planktonic (free swimming) organism into complex (a surface attached community). These changes are then reflected in the new phenotypic characters developed by biofilm bacteria and occur in response to variety of environmental signals. But biofilms not only consist of bacteria or even a single species of it only. It can be a multispecies complex having all types of microorganisms in it like fungi, algae, archae, protozoa, etc.

Once a free floating cell starts a biofilm or becomes a part of an existing one, it uses different genes to create protein and other surfaces that will help to adapt its new lifestyle like some genes control whither a microbe such as bacterium can move on its own, while others can command the cell to go into a dormant state if conditions are harsh.

Biofilm contains extracellular polysaccharide substances, also called as EPSs which is a part of a sticky matrix of sugars, proteins and other genetic material like extracellular DNA. EPSs not only help hold the cells of biofilm together but they also play a significant role in protecting the colony. The cell uses EPSs to itself better and make it easy for other cells to join the colony. The development of biofilms consists of different stages. In the first stage a free swimming cell gets attached with a solid surface submerged in a liquid or moist medium at the second stage it forms microcolonies after that coated themselves with sticky matrix of EPSs and then start maturation and finally the last and most important stage occurs that is dispersion which helps this community to divide into multiple short aggregates which further continue the growth of new colonies of biofilms.

Bacteria use complex chemical pathway called “heme nitric oxide/oxygen (H-NOX)” binding domain to form bio-films. Bacteria uses chemical regulator on this pathway to affect biofilm gene expression and to activate biofilm chemical messenger molecules. The chemical type of communication in bacterial biofilm is called as “quorum sensing” through which they transcribe their genes in one another and perform same functions at the same time just like a community. Considerable evidence exists in the scientific literature that implicates biofilm as being responsible for a variety of chronic infections associated with medical devices, hospital equipments and other households as well as workplace counter tops. There are certain evidences linking biofilm to diseases such as otitis (common ear infection), bacterial endocarditis, cystic fibrosis and some other chronic infections.

Ongoing biofilm research is primarily focused on the two things, firstly, on the development of physiochemical characteristics of the biofilm and secondly, the most important and challenging question, that how to disperse this bacterial slime layer which is responsible for their antibiotic resistance as well as resistance from immune defense and certain herbs also. Staphylococcus. epidermidis, a normal flora of healthy human skin and mucosal microbial communities has emerged as a common cause of nosocomial infections, mostly occurring in immunocompromised hosts. But, in S. epidermidis, biofilm formation is regarded as a major pathomechanism. Similarly, certain other pathogens like S. aureus and opportunistic organism P .aeruginosa also potent producer of biofilm and can cause serious infections due to this characteristic.

Our laboratory at the Department of Microbiology, Federal Urdu University, Karachi, is actively engaged in screening this nasty feature of biofilm production in clinically important bacteria and has also successfully applied some plant originated material that has got anti-biofilm forming activity and therefore can be effective to therapeutically manage the infection. Our laboratory has also produced few research papers of national and international repute in collaboration with other institutes regarding this issue. Medicinal plants derived com-pounds have increased widespread interests in the search of alternative antibacterial agents because of the per-ception that they are safe and have a long history of use in the folk medicine for the treatment of infectious dis-eases. So far, most studies have focused on the observation of antimicrobial activity of herbs taken as single unit but not in combination, such as herbal recipes. This study is, therefore, undertaken to investigate the anti-biofilm potential of traditional herbs that have been employed for the treatment of wounds and skin infections against all important biofilm producing pathogens.

By using herbs to interrupt the nitric oxide pathway, we can easily disrupt the formation of biofilm. According to the different researchers, there are some anti-biofilm herbs that also help to remove painful toxins and to pro-tect vital organs. The herbs have been shown to reduce the river of some infections caused by multiple biofilm producing pathogens. The medicinal properties of these herbs are under consideration of different researchers due to their healing factors and killing abilities. Our past research works in this clinically significant issue support this view that there should be some herbal content needed to include in antibiotics which can act as anti-biofilm agents. Further research will definitely open new ways and avenues about its role which will hopefully be helpful in controlling number of chronic diseases and microbial infections.

The writer, Youhibba Fatima Abbasi, is a B.S. student at FUUAST University, Karachi, and actively engaged in microbiology research, while Sikandar K. Sherwani is a Faculty in FUUAST University and supervisor of BS/MSc projects.


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