Pseudomonas, the insecurity

Question

My daughter had a positive swab and after a short time also antibodies in the blood. Now we have inhalation of Tobramycin, Ciprofloxacin orally, home i.v. with Tobramycin and Ceftazidim and now inhalation of Colistin. If the Pseudomonas will now be positive for a longer period of time, is there still a chance of getting rid of it??
We are still inhaling Colistin for one year, under this, she is not going to be 100% negative. If now no antibodies can be found anymore, can one assume under the current inhalation therapy that it has gone away??
Thank you and regards, V.M.

[The question below has been asked just after the question above, so that we assume, that these question are connected]
"Pseudomonas--I refer to my former question. My daughter has now received an i.v. therapy with Tobramycin and Colistin. Does it make sense to change every 4 weeks from Colistin to Tobramycin?
Can it be that it is only suppressed and one year after the complete finishing of the antibiotic treatment it is there again?"

Answer

Hello,
obvisouly there is an infection with Pseudomonas underlying after a positive swab and the PSA-antibodies found in the serum.
The procedure of your CF-center is well comprehensible.
The inhalative antibiotic treatment with e.g. Colistin/Tobramycin alternating has to be performed over a longer period of time in which no PSA germs can be detected anymore (4 samples). If then no PSA germs can be found anymore, the inhalative therapy can be stopped and every 4 weeks it is searched for the PSA germ. After 4 negative swabs in a time period of 6-12 months, the anti-PSA therapy can be finished.
The chances of success for an eradication are great. A guarantee for the eradication of a PSA infection/colonization, cannot be given, but one thing is for sure: the number of germs is suppressed in any case and the infection with the PSA is pushed back.
Even if the PSA germ has been found for a longer period of time, there is always the possibility to eradicate the PSA germs with the by you mentioned antibiotic regimen.
If no PSA antibodies can be found anymore and there is no microbiological detection of the germ anymore, one can assume that the eradication was successfull.
Only if after cessation of the inhalative antibiotic therapy there is no PSA germ in several swabs anymore and additionally the PSA antibodies are negative, the eradication has been successfull. The PSA antibodies are not the most important feature, but the negative finding of the germ.
The next question can be answered as follows:
One can inhale with Colistin for one year in case of a PSA infection of the lung.
It is common, to change the inhalative antibiotic every 4 weeks. The reason for this is the avoidance of resistances. With such an inhalative regimen the chances of survival of the PSA germ are reduced. This regimen is in general successfull for the eradication. With a high probability the PSA germ cannot be found anymore then.
Your CF center will discuss the further procedures with you. I cannot add anything to the recommendations of your CF center.

Best regards,
Dr. H.-E. Heuer

28.09.2015