Bacteria form biofilms to create an "ideal environment for creation of nutrient gradients, exchange of genes, and quorum sensing" (Emerging Infectious Diseases). Essentially, it's a protected community of bacteria that work and grow together. These communities grow best between a solid surface and a liquid medium - making catheters inserted in the bladder a prime target for biofilm formation. These biofilm infections on catheters are especially dangerous because "they resist the immune response and traditional antibiotic treatment" (Journal of Bacteriology). Hospital patients with catheters are especially at risk to these types of infections due to weakened immune systems and increased exposure to dangerous bacteria (like Pseudomonas aeruginosa) from healthcare workers and contaminated equipment. P. aeruginosa infections can lead to various health complications, the most dangerous being pneumonia and sepsis following an infection in the blood (CDC).
Fortunately, Maryland microbiologists have targeted a molecule produced by P. aeruginosa that plays a central role in biofilm formation on catheters. The molecule, cyclic-di-GMP (c-di-GMP) is regulated by several genes that affect bacterial colonization of the urinary tract. The team from Maryland tested catheter infections in mice bladders by P. aeruginosa by comparing "bacterial burden in the bladder and kidneys" between low levels of c-di-GMP and high levels. As predicted, the mice infected with P. aeruginosa containing high levels of c-di-GMP exhibited significantly more bacterial biofilm infections than the mice with low-level c-di-GMP.
Although the scientists were able to clearly expose c-di-GMP as a biofilm regulator, the target on which c-di-GMP acts to influence biofilm formation is still unknown. "In test tube studies, c-di-GMP influences biofilm formation by acting on bacterial pili and flagella... However when the investigators used mutant bacteria that could not make functional pili and flagella, the bacteria could still infect the mice" (American Society for Microbiology).
Solving the mystery is the next step to preventing catheter-related biofilm formation, especially in hospital patients. Check out the video below for an in-depth description of biofilms, how they are formed, and why they are advantageous for bacteria to produce.
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