Side effects after long-term therapy with azithromycin??

Question

Hello,
my 12-year-old son is chronically colonized with Pseudomonas aeruginosa (PSA) for two years. Since 6/2010 two times capsule-forming germs have been found in the throat swab. Since then he takes additionally azithromycin 250mg every second day besides Colistin and DNAse.
As this therapy is planned as a long-term therapy we ask ourselves:
Which side-effects does the drug have (arthropathy of the joints? Colonization with Streptococci? Occurence of resistance?) ?
Is there an alternative to this kind of PSA-therapy??
Many thanks for your feedback.

Answer

Hello,
the therapy with azithromycin is a common therapeutic modality in patients with CF. The reason for this is the fact that the substance has antimicrobial as well as anti-inflammatory features and in addition influences the production of mucus of the epithelial cells. Until now, azithromycin has been used with success mainly in patients with chronic colonization with Pseudomonas. Patients profit under a therapy with azithromycin clinically via a lower rate of pulmonary exacerbations, better gain of weight or both and via a better lung function and quality of life. In addition, newer investigations show, that patients require less freuently oral antibiotics under azithromycin.
The long-term therapy is tolerated well in general. Described are impairment of the gastro-intestinal tract, like loss of apetite, nausea and diarrhea, which can often be relieved via change of the dosage/intervals. Arthropathies are not described. Under a long-term therapy the bacterial flora does not change significantly, even if macrolide-resistant [azithromycin belongs to the group of makrolide antibiotics] Staph. aureus and makrolide-resistant unclassifiable Haemophilus influenzae can be found more frequently. This change is expected, as well as the more frequent finding of a change and resistance development of the normal bacterial flora (Streptococcus viridans, other groups of Streptococci). The clinical importance of these changes is until now not clear however. As latest investigations show the long-term therapy with azithromycin (6-12 months) is also a risk factor for the colonization with Aspergillus fumigatus and probably also for the development of a bronchopulmonal Aspergillosis. Regarding this, an increased alertness and regular controls of the sputum are necessary. In any case an outweighing of the ratio costs/benefits concerning the ongoing and duration of the therapy with azithromycin has to be done. Mostly the positive effects overweigh. A real alternative for the (additional) therapy with azithromycin in case of chronic colonization with Pseudomonas does not exist.
Yours sincerely,
Dr. Helmut Ellemunter

09.02.2011