This medication, which is called immunosuppression, has the unwanted effect of increasing the risk of infection in those taking it.
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.
This is why cystic fibrosis centres and clinics should offer separate clinics for cystic fibrosis patients according to whether or not they have Pseudomonas and to try to determine whether the strain is known to be more passable from one patient to another.
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 is decided on an individual basis and should be discussed with the transplant centre.