Stopping B. cepacia in its tracks
People with cystic fibrosis are vulnerable to lung infections which can be picked up by coming into direct or indirect contact with other people with the condition. While these bugs are usually harmless to people who don't have CF, they can settle in the lungs and be harmful for those who do. One of these is a group of bacteria called Burkholderia cepacia complex (BCC), sometimes known as B. cepacia.
Will, a character in the recent film about a couple with CF, ‘Five Feet Apart,’ has B. cepacia. That’s why we’re giving you the lowdown on what we know about the bug and how the research we funded is helping to stop it in its tracks.
Five things you might not know about B. cepacia
1. B. cepacia is hard to treat and can stay in the body for a long time. It is difficult to treat as it is resistant to many antibiotics. There is evidence that it can become dormant or inactive within the body but then come back. For example, after a course of treatment, and being tested as clear from the infection, it can ‘pop up’ again in the same person. Left untreated, B. cepacia can lead to a worse decline in lung health than in those who don’t have it.
2. The effect B. cepacia has on people with CF is hard to predict. Burkholderia cepacia complex is called a ‘complex’ because there are many species of Burkholderia bacteria. Some species are more harmful than others. Even within the same species of Burkholderia, different ‘strains’ (variations within the species) will have different levels of toxicity, and it will affect different people with CF differently.
3. B. cepacia can affect how well people do post-transplant. Studies have found that people with B. cepacia are at a greater risk of post-transplant complications than those who do not have the infection. In light of this, being infected by B. cepacia will be taken into consideration during transplant discussions.
4. B. cepacia was the first bacteria discovered to be passed between people with CF, instigating the ‘cross-infection’ rules that every person with CF and their families are advised to live by. Other bacteria are also known to be passed between people with CF, including the bugs Pseudomonas aeruginosa and NTM. B. cepacia is also present in the environment, particularly soil.
5. The first B. cepacia complex bacteria was discovered by Walter Burkholder in 1950. He was an American plant scientist who identified it on the skin of onions. It was later discovered to infect humans. The bacteria were first known as Pseudomonas cepacia.
How our lungs are kept clear of bacterial infections
The first line of defence to remove inhaled bacteria from the lungs is to physically and literally sweep them away. This is usually done by the movement of the cilia in the lining of the lungs and the movement of mucus. The next step is to activate the body’s in-built defence system, known as our immune system. There are cells in our immune system whose job it is to engulf bacteria and break them down to their constituent parts, stopping their ability to damage our body. If this doesn’t work a complex system of further defences is activated.
As bacteria are very good at side-stepping our natural defences, antibiotics give our immune system a helping hand in killing them. Once the bacteria is removed and disarmed the natural defences within the immune system stand down.
How B. cepacia causes problems for people with cystic fibrosis
People with CF are vulnerable to lung infections. The thick sticky mucus that clogs the lungs in people with CF makes it difficult to clear away infections – the cilia can’t sweep the bacteria away properly. This means that the bacteria have a chance to become ‘settled’ and defend themselves in their new environment.
When they become engulfed by our immune cells, B. cepacia uses clever defences to get around it. Usually, once engulfed, bacteria are kept contained within their own compartment in the cell, like a prison cell or dungeon within a castle, enabling our immune cells to kill the bacteria and prevent it from damaging our lungs. However, B. cepacia attacks the rest of the castle by firing out rockets from within its prison cell. The damage caused by the rocket fire ultimately causes inflammation and lung damage (the main cause of death in cystic fibrosis).
Firing rockets is a common attack system for many bacteria that scientists already know about. However, the ammunition within the rocket is different for each bacterium. In research funded by the Cystic Fibrosis Trust, Professor Miguel Valvano at Queen’s University Belfast identified the ammunition in the rockets fired by B. cepacia for the first time.
Why unravelling B. cepacia’s battle strategy matters
Although scientists know that bacterial infection causes inflammation, they don’t fully understand the ‘bit in the middle’ – in other words, how each bacterium actually triggers the inflammation to take place. Discovering the ammunition in the rockets of B. cepacia is an important step in doing this – once the whole battle plan of B. cepacia is laid out, researchers can work out ways to sabotage it.
Following a two-year research grant of £139,000 from the Trust in 2014, Professor Valvano has since been awarded a £343,000 grant from the Medical Research Council to explore the damage B. cepacia causes the immune cells in more detail. The end result will be to develop treatments to prevent or correct the immune cell damage. In turn, this will reduce the inflammation and lung damage caused by B. cepacia in people with cystic fibrosis.
Please donate today to support ground-breaking research like this. With your help, researchers are working to develop treatments for infections like B. cepacia to help people with CF live longer, healthier lives.