Susceptibility for Pseudomonas

Question

Dear experts,

is it true that some CF patients are more susceptible than others? Is there a correlation with susceptibility for PSA and certain genes?
Our 2-year-old son with CF has already had two times Pseudomonas aeruginosa in the throat swab. And that, even if we are very cautious and stick to all the hygiene rules. It is frustrating, if one does so much in order to avoid the Pseudomonas and it can be found in spite of this!
If one would know, that there would be a genetic predisposition for Pseudomonas colonization, so that one could not avoid it via hygiene rules anyhow, we could relax our efforts probably a bit and could our son let play like the other children in puddles, swimming pools, sand boxes and baby pools….?

Many thanks for your opinion.

Answer

Hello,

it is correct, that some patients are more susceptible for a PSA infection than others. It used to be that nearly 80% or more of CF patients had a PSA germ at the age of 18, however this has changed drastically in the last years.

Reasons for this are for sure:
- Respecting hygiene rules
- Early intervention in the very susceptible baby phase
- Early antibiotic treatment of bronchopulmonary infections, mostly infections with Staphylococci
- Good nutrition and good thriving
- Inhalative therapy
- Physiotherapy
- Newborn screening!

In Germany there are in the meantime centers, that do not care for CF patients positive for Pseudomonas under the age of 10.
As one cannot describe the exact reason of the affinity of the CF mucosa for the colonization/infection with Pseudomonas aeruginosa, one focused on hygiene and rainwater collectors, puddles etc.
It is correct, that a healthy handling with hygiene has a great meaning, such as washing the hands after having used the toilet, as well as after contact to animals and always before eating. This is sufficient.
The cross-infections in rehabilitation facilities have been regarded to be critical for years: now rehabilitation stays are offered, where the CF patients are seperated according to their colonization status with PSA. Furthermore, the danger of infection in the centers has had certain consequences: via the separation and face masks and "no touch" a real prevention could be achieved.

Genetically, one can to my knowledge not define a certain mutation that is correlated with an increased infection with the PSA germ.
That PSA germs are found in the throat swab and then never again, is not seldom; even without antibiotic intervention.
In spite of this, we are always searching early for this germ and treat it then.
However most important is not the single diagnostic tool like microbiology, however most important is the overall clinical picture.
One will have a very close control via the CF center in the first moths and years of life and will also treat bronchopulmonary virus infections early with antibiotics. Then the PSA germs will have few chances for colonization and infection.
An early finding of a PSA colonization/infection does in no case mean the beginning of a PSA episode, that cannot be influenced!
Just an example: a 3.5-year-old girl with CF certainly has the finding of this germ. The child is not really ill! Anti-i.v. antibiotic treatment at home for 14 days. Eradication! Then after 10 years again PSA colonization, again i.v.-intervention, then never again. The girl is now 19 years old and really healthy. No serological hints for PSA-infection! Sports/hygiene and good nutrtion. One could report endlessly about such examples.
Therefore: follow "normal" hygiene and regular controls in the CF center, liberal play with water etc. and do not be irritated by one or two PSA findings.
There are numerous CF-centers, that have 18-year-old CF patients without PSA-finding (about 60% and more)
The PSA-infection is no longer the limiting factor of a life with CF! Therefore green light for a life with puddles etc.
Genetic does in general play a role for the prognosis. The compound-mutations have, carefully speaking, a better prognosis. However we cannot correlate certain mutations to a PSA career!

Best regards,
Dr. H.-E. Heuer

12.06.2015