A group of researchers from Switzerland made a discovery that provided new insights into the infection strategies used by pathogens. Their study found that the bacteria that cause cholera can form a novel type of community on surfaces.
New Insights into Cholera Infection
In the past, scientists thought that bacteria tended to create biofilms as a defense and protection for themselves. The team led by Prof. Knut Drescher at the Biozentrum, University of Basel, demonstrated the ability of bacteria to form a biofilm, which can be deadly to the immune cells.
In this study, the scientists used Vibrio cholerae, the pathogen that causes the intestinal infection cholera. They focused on phagocytic cells called macrophages to better understand biofilm formation.
When the bacteria accidentally encounter a macrophage, it attaches itself to the cell's surface using a feeler. Then the bacteria begin to divide and weave their feeler-like projections. This makes the newly-discovered biofilm different from the known bacterial community since its extracellular matrix structure produces a meshwork. Previously known biofilms are typically slimy matrices made of sugars and proteins.
Another trait discovered in the study is that while the known biofilms are created as a defensive strategy, the new bacterial community on immune cells is aggressive. Over time, macrophages are completely encased by the biofilms created by the cholera pathogen, leading to cell death.
Although it was found that the bacterial community actively invades and destroys the immune cells in the human host, scientists still do not understand the exact mechanism behind this process.
In response to this challenge, the research group analyzed all 14 known toxins released by the cholera bacteria. After meticulous investigation, it was revealed that hemolysin was the culprit in these attacks. This particular toxin creates pores in the protective covering of the immune cells, leading to their death.
Scientists also rely on humans being the only known host of the cholera-causing pathogen. They developed a human intestinal organoid model, which was used to demonstrate the ability of Vibrio cholerae to form deadly biofilms on macrophages following the colonization and disruption of the human intestinal wall.
According to Drescher, the attacking strategy employed by the bacteria can affect the progression of cholera infection. He also reveals that his team plans to explore the ability of other pathogens to create aggressive biofilms. When the strategies of the pathogens are deciphered, experts can develop new approaches to fight them.
Are Biofilms Threatening?
A lot of bacteria can exhibit the ability to produce biofilm as a type of defense strategy. Biofilms are present in materials we usually encounter, such as slimy stones in water, dental plaque, and even our natural intestinal flora.
Since bacterial biofilms can resist antibiotics, they can pose a health threat in clinical settings once they invade catheters, implants, and surgical devices. The colonization ability of these pathogens enables them to invade the human body and cause infections that the immune system or antibiotics cannot easily fight.
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