The role of antimicrobials on different microorganisms
Of the antimicrobial compounds, antibiotics are the best known - although they are not the only ones. However, as we already talked about in another article, the recent concern about the resistance of microorganisms to antibiotics it is generating a need to think outside the box when it comes to health. How is this happening and what can we do to solve this problem?
The first line of defense
Compostos antimicrobianos são produtos químicos projetados para ter toxicidade seletiva contra microrganismos. Significa que são capazes de afetar células microbianas, mas não células animais, como as do ser humano, ou vegetais.
Isso pode se dar pelo ataque de agentes químicos a estruturas específicas nas células de patógenos de interesse (como os grupamentos sulfidril na parede celular), disrupção de uma área de expressão genética imprescindível para o seu ciclo de vida (como a duplicação do DNA), entre outras. Assim, é um pouco óbvio concluir que quanto mais potente a forma de uma bactéria proteger sua estrutura no meio dessa guerra, maior resistência aos ataques antimicrobianos ela terá – e consequentemente, maior sua chance de sobrevivência.
When we talk about protecting bacteria from external agents, we are dealing with single-celled beings with different characteristics in their cell wall. It is the cell wall that forms the bacteria and provides the first barrier for the protection of its intracellular material, due to its rigid structure. The compounds in greatest abundance in the cell wall are peptideoglycans, and differences in the peptideoglycan network can characterize bacteria as more or less resistant to external agents.
A Gram stain is a technique developed in the 19th century by Hans Christian Gram that allows to differentiate bacteria with a thicker cell wall (gram positive) and less thick (gram negative) in peptideoglycans. This variation is added to the presence of a double or mono-layer of phospholipids, providing greater or lesser resistance of the bacterial cell wall to external agents.
But physical blockage is just one way that bacteria can protect themselves against attack by antimicrobial agents.
A resistance acquired by microorganisms
As previously presented, antibacterial agents can be designed to target different structures in the cellular constitution of bacteria, thus providing a well-targeted control of pathogens. The versatility of these microscopic beings, however, allowed them a wide range of mechanisms to fight extinction. Below are some examples of these mechanisms:
– Chemical modifications of antimicrobial compounds, through interaction with the extracellular environment. Depending on the severity of changes in the microenvironment, such as a change in pH or secretion of oxidizing agents, the destruction of antimicrobial molecules or particles.
– Reduced cell permeability antibiotic agent, either by structural modifications in the cell or through efflux pumps. Despite an energy cost that is often very expensive for the cell, the latter is a mechanism that prevents the entry of antimicrobial agents in the cell in addition to the physical barrier. Efflux pumps exist for the most varied compounds, from complex organic molecules to ions.
How bacteria resistance works
Understanding the mechanisms by which bacteria are able to resist threats is central to designing antimicrobial compounds that act in their control. Knowing that through genetic exchanges between bacteria these resistances can be passed on, helps us to understand the billions of years of survival of these beings in harmful environments (take a look at this video where Harvard researchers demonstrate this effect in a visual and accelerated way)!
There is a tendency in literature research to demonstrate that antimicrobial agents, and especially antibacterial agents, work better and prevent the acquisition of resistance when acting on multiple control fronts. "Microorganisms simply cannot find a way to bypass more than three independent mechanisms of action simultaneously," says Professor Dale Boger, in your interview to the Science. “Even if they found a solution for one of them, they would still be eliminated by the other two!”.
TNS works with antimicrobial agents for fungi and bacteria that act on multiple control fronts, from rupture of the cell wall to the suppression of genetic coding and cell respiration. In addition, the high surface area of the nanomaterials employed, as in the case of silver nanoparticles, makes these additives economically attractive and highly versatile. Get in touch to find out more, our consultants are ready to serve you!