Cross-infection, or cross contamination, occurs when one person spreads an infection to another, either directly or indirectly. Find out how cross-infection affects people with cystic fibrosis, and what is done to combat the issue.

For people with cystic fibrosis, cross-infection can be very harmful and poses a particular threat. This is why people with cystic fibrosis should not meet face to face.

Read our cross-infection policy

  • What is cross-infection?

    People with cystic fibrosis are vulnerable to different bacteria or 'bugs', which grow in their lungs. While these bugs are usually harmless to people who don't have cystic fibrosis, they can settle in the lungs (colonise) and be harmful for those who do. These bugs can be easily transmitted from one person with cystic fibrosis to another.

    There is less risk of transmission of 'bugs' in an outdoor environment, but meeting indoors, travelling with other people with cystic fibrosis, or spending time with them socially has a high level of risk. The risk of cross infection increases the longer people with cystic fibrosis are in close proximity to one another.

    Bugs such Burkholderia cepacia complex and Pseudomonas aeruginosa can be transmitted from person to person by close personal contact and activities such as meeting, sharing rooms, medical equipment, cutlery or crockery; and by kissing or coughing.

  • Which bugs can be passed on through cross-infection?

    There are a number of infections or bugs that can affect people with cystic fibrosis even though they are usually harmless to people who don't have the condition. These include:

    • Pseudomonas aeruginosa (Pseudomonas)
    • Mycobacterium abscessus (M. abscessus)
    • Burkholderia cepacia complex (B. cepacia)
    • Aspergillus fumigatus (Aspergillus)

    Find out more about the bugs that can affect people with cystic fibrosis, how common they are in the UK and what research Cystic Fibrosis Trust is funding to develop more effective treatments to combat them.

  • Transplants and cross-infection

    People who have had a lung transplant need to take powerful medication for the rest of their lives to dampen down their immune system and to protect the transplanted lungs from rejection. This medication, which is called immunosuppression, has the unwanted effect of increasing the risk of infection in those taking it.

    It is therefore important that after having a lung transplant people avoid, where possible, any non-essential contact with anyone who has an active infection, especially winter bugs, colds and flu. Although the annual flu jab is essential to protect against severe flu it does not protect people from seasonal bugs and colds.

    After a lung transplant it might also be necessary to avoid close contact with other people with cystic fibrosis if their lungs are infected with particular bacteria or fungi. This is decided on an individual basis and should be discussed with the transplant centre. Some people after lung transplant may continue to carry bacteria or fungi in their sinuses or upper airway or their newly transplanted lungs which might pose a risk to other people who have had a lung transplant. If this is the case some restrictions on contact with them might be advised. Again this is individual and should be discussed with the transplant centre.

  • Why is avoiding cross-infection important?

    Repeated lung infections in cystic fibrosis cause lasting damage that can be very difficult to treat. Infections from certain bacteria can also have additional serious health implications. When the lungs become very damaged, a lung transplant may be the only remaining treatment option. However, there are not enough donor lungs available for everyone who needs them. A lung transplant is not a suitable treatment option for everyone and is not a cure for cystic fibrosis.

    Avoiding lung infections is therefore extremely important for people with cystic fibrosis, to help keep their lungs as healthy as possible for as long as possible.

  • How can people with cystic fibrosis reduce their risk of lung infections?

    Avoiding contact with other people with cystic fibrosis is a very important way to avoid lung infections. This is why CF centres and clinics in the UK are very careful to segregate their patients (keep them apart from others with CF when they are in hospital).

    Cross-infection can be significantly reduced by keeping people with CF apart from others with CF, not only in hospital but in day-to-day life, and by careful attention to good hygiene such as hand washing.

    The longer someone with CF is near to someone else with CF, the greater the risk of cross-infection. The risk of passing on infections is higher indoors than it is outdoors, but no environment is completely safe.

  • Why is cross-infection guidance different to the Government's COVID-19 guidance?

    Guidance to wear masks, socially distance and avoid meeting indoors has been really important in reducing infection rates of COVID-19. However, when coronavirus rates were higher and fewer people had been vaccinated, people with CF were advised to ‘shield’ and avoid all social contact altogether. This is similar to cross-infection guidance – completely avoiding meeting with people when there might be a risk of very serious infection.

    Now that most adults with CF have been vaccinated against COVID-19, their risk of serious illness if they contract COVID-19 is much lower. Unfortunately, this is not the case for some of the bugs that can be passed on through cross-infection. Children with CF are not thought to be at risk of significant illness from COVID-19 but, again, children with CF are still at risk from the bugs that could be passed on by cross-infection. 

  • Would meeting outdoors with masks on, and staying 2m apart, remove any risk from cross-infection?

    We can’t know for definite that this would be safe – there isn’t any existing scientific evidence to prove this. Doctors and scientists can’t test it out either, because to do this people with CF would have to be put at risk, and that wouldn’t be the right thing to do. We are still learning about how some of the bugs that affect people with CF are transmitted, and we do know it’s possible to pick some of them up from surfaces as well as in the air.

  • I’ve considered all the risks and I want to meet with someone else with CF – is there any advice for doing this as safely as possible?

    All individuals with CF can make their own decisions about infection risk (as long as their choices don’t put others unknowingly at risk) – what is important is that you have the information you need to help you make an informed choice. It’s important you receive advice personalised to you.

    Your CF team are the best people to talk to about this, as they know your own CF health. You should also bear in mind that CF teams wouldn’t be able to tell you even if they knew someone you planned to meet had an infection, because of patient confidentiality.

  • CF treatment has improved so much – is cross-infection still as important?

    Prior to our knowledge about cross-infection, people with cystic fibrosis often mixed with each other, even attending holiday camps. Understanding cross-infection, together with the development of new and better treatments, means people with cystic fibrosis are living longer than ever before.

    Despite all the advances in CF treatment, some of the bugs that affect people with cystic fibrosis can be very serious, and very difficult to treat. Some rare infections can shorten life expectancy very significantly, so it remains really important to reduce risk wherever possible. It’s not possible to remove all risk from day-to-day life, but where we know about a very serious risk, such as the way certain bugs can be transmitted between people with CF, we can take steps to reduce the risk.

    We continue to fund research to help us understand the bugs that cause serious infections in people with cystic fibrosis. 

  • If someone has recently provided a clear sputum sample, does this mean they are free of any dangerous infections and it would be safe to meet with them?

    It still wouldn’t be possible to guarantee this would be safe – it is possible to pick up an infection at any point. It would also depend what the sputum sample was tested for, as not every sample is tested for every possible bug.

  • How does Cystic Fibrosis Trust manage cross-infection risk at events?

    Our policy for indoor events is clear that we can only have one person with CF at any indoor event. For some major outdoor events, it would be unfair to limit access to one person with CF, especially as some of the outdoor events we’re involved in are very large (e.g. the London Marathon).

    If you are organising or taking part in an event, please read our cross-infection policy.

    We have our own policy for outdoor events and ask all those taking part in the event to follow it. If our staff are aware of multiple people with CF at one outdoor event, we do all we can to manage the risk and ensure those people are a safe distance apart from each other at all times, as well as asking people with certain bugs not to attend at all. We also let people with CF know that there is likely to be someone else with CF at the event.

  • Nontuberculous Mycobacterium abscessus (NTM)

    A working group brought together by Cystic Fibrosis Trust and including healthcare professionals and experts on microbiology and cross-infection has released new advice to help protect people with cystic fibrosis from catching infection with NTM.

    Read the guidelines on NTM infection issued by Thorax, the international journal for health professionals working in respiratory medicine.

Consensus documents

Our consensus documents are designed for clinicians and allied health professionals involved in treating people with cystic fibrosis.

Emma's story

Read a personal account of cross-infection and why it's important to consider how it affects people with cystic fibrosis.

Cross-infection at events

Find out more about how we reduce the risk of cross-infection at events.

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