Enterobacter chloacae and Serratia marcescenz and S. liquefaciens

Question

Dear expert team,
I suffer from CF and I am Pseudomonas negative and have again and again the above mentioned germs in the sputum. Where can one get those bacteria from, they are intestinal germs, aren’t they? The FEV1 value is stable, however I cough more and have difficulties in bringing up the secretions. Inhalations of tobramycin is the current therapeutical regimen of my CF center. Since the occurrence of those germs (about 6 months ago for the first time, then again and again), I feel exhausted and have aching arms and legs. Is the inhalation of tobramycin sufficient and if yes, why can those germs still be detected under the therapy with tobramycin? This seems to be a poof, that there is no efficacy?
Many thanks for your efforts!

Answer

Hello,
as you for sure know, kinds of bacteria love to grow in the CF lung, that do otherwise never occur in healthy people. Together with the usage of antibiotic drugs, that are a necessary and sensible part of CF treatment, there emerge of course also niches where bacteria can colonize, that normally never occur. In here belong the by you mentioned germs, that are partly belonging to the group of enterobacteria, that occur in the gut but normally not in the lung.
Now one has to ponder: what do these germs do in the lung, are they really harmful and how could one get rid of them. In here it is difficult, because we do often not have an unambiguous answer on the first question. Do they really harm or are they harmless? Do they lead to progression of the illness or are they rather harmless. Of course, one tends to wish to get rid of them, because for what reason should they be in the lung.
Then the next question arises: which antibiotic should be used in case of the frequent multi-resistance and does one not cause more damage with the antibiotic probably, knowing that one often cannot get rid of them even after a longer period of treatment.
Therefore it is true, that one has to ponder the single case and the physician in the CF center has to decide in each individual case when a therapy is sensible and when not.
I do not believe, that your actual symptoms are really caused by these germs, however one could think about changing the inhalation of tobi to another antibiotic in order to see, if the symptoms are getting better.
Best regards,
Prof. Dr. Joachim Bargon

27.02.2016