Lung-invading Hospital Microbe Unveiled
Horrifically, each year approximately five million people perish worldwide due to the contamination of antibiotic-resistant germs. One such menacing germ is Pseudomonas aeruginosa. Researchers in a lab scrutinize how this bacterium bypasses the lungs' defense lines.
Pseudomonas aeruginosa is infamous for being among the world's deadliest hospital bugs. This bacterium infects respiratory tracts and lungs, posing serious risks for individuals with compromised immunity. A Swiss research team has recently uncovered the means by which this bacterium invades the lungs. They cultivated lung organoids and observed the bacterium's progress as it breached the lungs' defense wall. Their findings were published in the journal "Nature Microbiology".
Our respiratory system's entire tract is shielded with a specialized mucosa, safeguarding the deeper layers of lung tissue. This mucosa is composed of countless ciliated cells interspersed with mucus-secreting gland cells.
These gland cells' mucus obstructs microorganisms and pathogens from penetrating the lung, forming a nearly impregnable barrier. However, Pseudomonas aeruginosa manages to penetrate this barrier.
Mortal germs
These germs are often referred to as hospital-acquired pathogens, and the Robert Koch Institute reports that they are among the most common causes of hospital-acquired lung infections, particularly among the immunocompromised and those on ventilators, who face increased risk. The World Health Organization (WHO) lists Pseudomonas aeruginosa among the top twelve most dangerous bacterial pathogens worldwide that are resistant to multiple antibiotics.
But, how does this bacterium weasel its way past the mucus barrier? Insights emerge from the lung organoids of a Swiss research team, cultivated from human stem cells and infected with the bacterium. "We have cultivated human lung microtissue that echoes the infection process in a patient's body," Urs Jenal from the Biozentrum of the University of Basel was quoted in a statement. "These lung models allowed us to discern the bacterium's infection strategy."
Cunning strategy
Indeed, the bacteria utilized a cunning strategy to penetrate the tissue barrier. As detailed in the study: "In the early phase of infection, P. aeruginosa spreads rapidly by consuming the nutrients present in the mucus layer." In this initial phase, only a handful of bacteria come into contact with the tissue surface, and the tissue remains unscathed.
"As the infection process progresses, P. aeruginosa begins to adhere to and attack the underlying epithelial tissue, possibly because the mucus is depleted, resulting in a growth stop for the bacterium," the study continues. Then, the bacteria employed the mucus-producing gland cells as covert agents. "By targeting the gland cells, which represent only a minor fraction of the lung mucosa, the bacteria can break through the defense line and create an opening," Jenal elaborates.
The pathogens assaulted the cell membranes with immense force, forging their way in, multiplying, and eventually causing the cells to explode and expire. The bursting of deceased cells led in turn to tears in the barrier, resulting in weak spots, which the bacteria swiftly exploited: They promptly colonized these weak spots, from which they expanded deeper into the tissue.
"Thanks to the development of human lung organoids, we now possess a greater understanding of how pathogens behave within human tissue and likely within patients," concludes Jenal. Human lung organoids and other organoids such as the kidney allowed researchers to examine the effect of antibiotics on tissue and, for instance, determine where and how bacteria survive during treatment. They will be vital for the future development of innovative and effective strategies for countering disease-causing agents.
Read also:
- The Robert Koch Institute highlights that multi-resistant germs, such as Pseudomonas aeruginosa, are among the most common causes of hospital-acquired lung infections, particularly affecting immunocompromised patients and those on ventilators.
- To combat these multi-resistant bacteria, education about proper hygiene practices is crucial in hospitals to reduce the risk of germ transmission. Strengthening the immune system through balanced nutrition and regular exercise can also enhance the body's ability to fight off infectious diseases.
- The findings from the Swiss research team's study on Pseudomonas aeruginosa suggest that developing innovative strategies could involve targeting bacterial adhesion to mucus-producing gland cells to prevent their penetration of the lung barrier. This could potentially lead to the creation of new antibiotics or approaches to protect against these deadly multi-resistant germs.
