[Bacteriological monitoring of the treatment of Pseudomonas aeruginosa infections with amikacin administrated at once-daily dosis in patients with cystic fibrosis].

The interest of the treatment with a single daily dose of amikacin (AMK) in cystic fibrosis (CF) patients with P. aeruginosa infections has been much debated. The aim of work was to study the efficiency of this treatment on (CF) patients with chronic bronchopulmonary P. aeruginosa infections previously treated for two weeks with the combination ceftazidime (CAZ 200 mg/day in 3 inj. IVD) and AMK (35 mg/day in one IV perf. of 30 minutes). The bacteriological supervision of this treatment was performed 1: by the determination of MICs before and after treatment, 2: by the decrease of P. aeruginosa colonization immediately after this treatment and during 11 months, 3: by the identification of P. aeruginosa strains with phenotypic methods (serotyping and antibiotyping) and with genotypic method (pulsed field gel electrophoresis). The use of AMK in a single daily dose in order to treat chronic lung infections colonized with P. aeruginosa susceptible to this antibiotic shows encouraging results as far as bacteriology is concerned: this treatment has given means to reduce colonization for a month in 15 of 18 patients. For 9 of the 18 patients, no P. aeruginosa strains were isolated for nine months. The serotyping and antibiotyping systems do not enable us to study the P. aeruginosa epidemiology. Genome macrorestriction fingerprinting of P. aeruginosa in pulsed field gel electrophoresis confirms that patient with CF were colonized with one or several clones. In our study no variation of these clones was noticed for the first eleven months. Genome macrorestriction fingerprinting appears to be one of the most effective methods for delineate strains of P. aeruginosa colonizing CF patients.