[Inhaled colistin in cystic fibrosis].
The clinical course of cystic fibrosis (CF) is characterised by chronic bronchial infection with Pseudomonas aeruginosa. Therapy with inhaled aminoglycosides was introduced to decrease the rate of infectious exacerbations and to delay pulmonary progression. However, development of resistance to aminoglycosides is frequent. Few investigations are available into the resistance profile under treatment with colistin. Antibiotic resistance to colistin was analysed in 44 adult CF patients treated with inhaled colistin. Resistance to aminoglycosides was observed in 86% of cases (38/44) before therapy and decreased to 43% (19/44) under treatment with colistin. Five patients (11%) developed polymyxin resistance. After cessation of therapy pseudomonas became sensitive to polymyxin within a few months and enabled colistin to be reintroduced. In addition, we performed a pilot study analysing the effect of inhaled colistin on the growth of pseudomonas. The number of Pseudomonas aeruginosa decreased from 16.7 million (CFU) bacteria per ml sputum to 2.9 million under therapy with colistin. There was a more than tenfold increase in bacterial counts after inhaled colistin was stopped. Genotyping revealed no change in the type of pseudomonas strains.


CONCLUSIONS
Development of resistance to polymyxin is not rare under long-term treatment with inhaled colistin and requires temporary interruption of therapy. Sputum cultures should therefore be tested regularly for polymyxin resistance in patients treated with inhaled colistin.
Tamm
M
M
Abteilung Pneumologie, Kantonsspital Basel. michaelt@mail.med.usyd.edu.au
Eich
C
C
Frei
R
R
Gilgen
S
S
Breitenbücher
A
A
Mordasini
C
C
D000280:Administration, Inhalation; D000328:Adult; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D003091:Colistin / Q000008:administration & dosage / Q000627:therapeutic use*; D003550:Cystic Fibrosis / Q000150:complications*; D004352:Drug Resistance, Microbial; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000209:etiology / Q000382:microbiology*; D008297:Male; D010865:Pilot Projects; D011113:Polymyxins / Q000627:therapeutic use; D011552:Pseudomonas Infections / Q000188:drug therapy* / Q000209:etiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D013183:Sputum / Q000382:microbiology
D000900:Anti-Bacterial Agents; D011113:Polymyxins; D003091:Colistin