Pseudomonas aeruginosa, mostly seen in nosocomial infections, causes important problems due to antibiotic resistance. In this study, susceptibility of nosocomial P.aeruginosa strains against ceftazidime, an antipseudomonal antibiotic, was investigated by Kirby- Bauer disc diffusion and E-test methods. Of the 71 P.aeruginosa strains 30 (42.2 %) strains were isolated from urine, 27 (38 %) from wound-abscess, 12 (16.3 %) from tracheal aspirates, 1 (1.4 %) from pleural fluids, 1 (1.4 %) from acid fluids. 42.3 % of the strains were sensitive to ceftazidime by disc diffusion method and 50.7 % by E-test method.

The difference between two methods was statistically significant (p<0.001) and E-test method was found to be more sensitive than disc diffusion method in the detection of ceftazidime susceptibility. In the empirical treatment of nosocomial P. aeruginosa infections, the use of ceftazidime should be based on the susceptibility test rather than its use as a first choice antibiotic.