The in vitro activity of ciprofloxacin aztreonam and nine other antipseudomonal antibiotics for pseudomonas aeruginosa from cystic fibrosis patients

Progressive respiratory failure associated with chronic colonization of the lung by Pseudomonas aeruginosa is the major cause of death in patients with cystic fibrosis. The length of pulmonary colonization with P. aeruginosa is associated with a shortened lifespan. the production of extracellular toxins, the induction of mucin production by respiratory epithelial cells, and the formation of immune complexes in the lung in response to Pseudomonas and it's toxins all implicate the organism as a pathogen in Cystic fibrosis. Investigations of the efficacy of new antibiotics in the treatment of cystic fibrosis pulmonary infections are ongoing at the University of Utah, where more than 200 cystic fibrosis receive medical care. Clinical trials during 1985 and 1986 centered around ciprofloxacin and aztreonam. Both of these new agents have significant in vitro activity against P. aeruginosa. The foremost objective of this study was to compare the in vitro susceptibility of P. aeruginosa isolates from cystic fibrosis patients to these new antibiotics and to other currently used or investigational antipseudomonal agents. It is important to describe susceptibility and resistance patterns in a population like this in which frequent and varied antibiotic exposure may lead to unique resistance patterns. In summary, this study had several purposes: 1.) To describe the invitro sensitivity of 79 isolates of P. aeruginosa from cystic fibrosis patients to ciprofloxacin, aztreonam and nine other antipseudomonal antibiotics; 2.) To assess the incidence of concomitant resistance between these new antibiotics and other antipseudomonal antibiotics, and 3.) to assess the potential for rapidly developing resistance to aztreonam during initial therapy.