Nav: Home

Calcium induces chronic lung infections

October 24, 2016

The bacterium Pseudomonas aeruginosa is a life-threatening pathogen in hospitals. About ten percent of all nosocomial infections, in particular pneumonia, are caused by this pathogen. Researchers from the University of Basel's Biozentrum, have now discovered that calcium induces the switch from acute to chronic infection. In Nature Microbiology the researchers have also reported why antibiotics are less effective in fighting the pathogen in its chronic state.

One of the most serious pathogens is the bacterium Pseudomonas aeruginosa, which frequently causes hospital infections and is notoriously difficult to treat owing to its multi-resistance to antibiotics. Although P. aeruginosa is responsible for a range of different infections in humans, it is the leading cause of chronic lung infections in immune-compromised patients.

Calcium induces acute to chronic virulence switch

In an early, acute stage of pneumonia, the pathogen employs a wide arsenal of weapons - so-called virulence factors - to invade the host and evade its immune system. During disease progression, the bacterium adapts its strategy by switching from acute to chronic virulence. It stops the production of virulence factors, such as bacterial injection apparatus and toxins and, instead, produces a protective matrix and reduces its growth rate. The environmental signals directing this transition were so far unknown. The team led by Prof. Urs Jenal, infection biologist at the Biozentrum of the University of Basel, has now identified calcium as a signal that specifically triggers the switch to chronic virulence.

"In Pseudomonas a central signaling pathway senses environmental information and ultimately determines whether the pathogen will undergo the acute to chronic virulence switch," explains Jenal. "Although the components of this pathway are well-known, none of the external signals modulating the switch are defined." The researchers have now discovered that a receptor located in the bacterial cell envelope monitors the calcium concentration in the environment and transmits this signal into the cell. Elevated calcium levels trigger the switch to a chronic program: The bacteria protect themselves within a biofilm structure, reduce their growth rate and by that increase their drug tolerance and persistence.

Cystic fibrosis patients harbor calcium sensitive bacteria

Finally, the researchers were able to demonstrate the clinical relevance of their findings. Patients suffering from cystic fibrosis develop lifelong chronic infections by P. aeruginosa, which permanently damage their lung tissue. "Most of the isolates from airways of CF patients have retained their calcium sensitivity," emphasizes Jenal. "We believe that this allows these bacteria to constantly adapt their virulence in response to the often changing conditions in the airways. One of the characteristics of cystic fibrosis is deregulated calcium homeostasis. We assume that elevated calcium levels in patients promote the switch from an acute to a chronic state of infection. This is of advantage for the pathogen, as it may ensure its long-term survival in the respiratory tract. At the same time, treatment of chronically infected patients becomes more challenging."
-end-


University of Basel

Related Bacteria Articles:

Conducting shell for bacteria
Under anaerobic conditions, certain bacteria can produce electricity. This behavior can be exploited in microbial fuel cells, with a special focus on wastewater treatment schemes.
Controlling bacteria's necessary evil
Until now, scientists have only had a murky understanding of how these relationships arise.
Bacteria take a deadly risk to survive
Bacteria need mutations -- changes in their DNA code -- to survive under difficult circumstances.
How bacteria hunt other bacteria
A bacterial species that hunts other bacteria has attracted interest as a potential antibiotic, but exactly how this predator tracks down its prey has not been clear.
Chlamydia: How bacteria take over control
To survive in human cells, chlamydiae have a lot of tricks in store.
Stress may protect -- at least in bacteria
Antibiotics harm bacteria and stress them. Trimethoprim, an antibiotic, inhibits the growth of the bacterium Escherichia coli and induces a stress response.
'Pulling' bacteria out of blood
Magnets instead of antibiotics could provide a possible new treatment method for blood infection.
New findings detail how beneficial bacteria in the nose suppress pathogenic bacteria
Staphylococcus aureus is a common colonizer of the human body.
Understanding your bacteria
New insight into bacterial cell division could lead to advancements in the fight against harmful bacteria.
Bacteria are individualists
Cells respond differently to lack of nutrients.

Related Bacteria Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...