RESUMO
The minimum inhibitory concentration of ceftazidime, was determined for 132 mucoid strains of pseudomonas aeruginosa (MPA) isolated from patients with cystic fibrosis (CF), using an agar tube dilution method. Using strains collected over a ten-year period, we found that 98 percent were susceptible to achievable serum concentrations with MIC50 and MIC90 of 1.2 and 3.1 ug/ml, respectively. Susceptibility of 60 of these strains was also determined for cefoperazone (100 percent susceptible), tobramycin (97 percent), and carbenicillin (83 percent). Susceptibility of stored strains was similar to that of fresh isolates. We have shown that strains of MPA in a U.S. population were more susceptible to ceftazidime than those currently reported from Europe where this antibiotic was introduced earlier. Cefoperazone, another third generation cephalosporin which has received less attention in the treatment of patients with CF, is as active as ceftazidime in vitro. These data provide a basis for determining the future impact of these agents on pseudomonas susceptibility (AU)
