Susceptibility of Pseudomonas aeruginosa to cefepime versus ceftazidime in patients with cystic fibrosis

Study Objectives. To compare the susceptibility of respiratory cultures of Pseudomonas aeruginosa obtained from patients with cystic fibrosis to cefepime versus ceftazidime. The pattern of cumulative resistance of aeruginosa to cefepime in patients who had received at least one treatment course of cefepime between two sputum cultures was also characterized. Design. Prospective consecutive data collection. Setting. University-affiliated cystic fibrosis clinic and medical center. Patients. Eighty patients with cystic fibrosis who had at least one sputum culture positive for R aeruginosa with reported microbiologic susceptibilities to cefepime and ceftazidime. Intervention. Patient data was collected and analyzed. Measurements and Main Results. Two hundred and thirty-one R aeruginosa isolates were collected over 6 months. A total of 16.4% and 8.7% of the isolates were nonsusceptible to cefepime and ceftazidime, respectively (p=0.01). In eight patients who had not received cefepime before the study period, nonsusceptibility was 11.8% and 27.2% before and after exposure to cefepime, respectively Conclusions. Susceptibility of P. aeruginosa isolates in patients with cystic fibrosis was lower with cefepime than with ceftazidime. Follow-up surveillance to determine changes in susceptability of P.aeruginosa isolates to cefepime is warranted.