Antibiotic treatment of chronic Pseudomonas aeruginosa infection in cystic fibrosis patients

The retrospective bacteriological results of 322 courses of anti-Pseudomonas aeruginosa chemotherapy in a cohort of 57 cystic fibrosis (CF) patients are reported. Tobramycin given as mono-therapy eradicated P. aeruginosa from the lungs of CF patients in 9% of the courses, whereas a combination therapy consisting of carbenicillin + tobramycin eradicated P. aeruginosa in 55% of the courses. However, the efficacy of the chemotherapy diminished successively when repeated courses of treatment were given. The efficacy of the carbenicillin + tobramycin combination in eradicating P. aeruginosa from the lungs of CF patients was compared with the efficacy of azlocillin + tobramycin and piperacillin + tobramycin in a prospective study. P. aeruginosa was eradicated in 78% of CF patients treated with carbenicillin + tobramycin, in 28% of CF patients treated with azlocillin + tobramycin, and in 33% of CF patients treated with piperacillin + tobramycin. However, the two latter groups of patients had on an average significantly higher numbers of P. aeruginosa precipitins in serum, indicating more severe infections. In CF patients where P. aeruginosa was not eradicated, a significant increase of MIC against carbenicillin, azlocillin and piperacillin was observed. There was a significant improvement of lung function and laboratory parameters reflecting diminished inflammation as a result of the treatment. 40% of the CF patients treated with azlocillin or piperacillin developed serum sickness-like symptoms.