Background: Pseudomonas aeruginosa is the third most common pathogen responsible for nosocomial infections and the prevalence of multiple resistant isolates has been increasing. Ninety-nine clinical isolates were studied in order to assess the current levels of susceptibility and cross-resistances of widely used antipseudomonal antibiotics against P. aeruginosa and to determine some resistance mechanisms by phenotypic methods.
Methods: MICs of isolates for nine antipseudomonal antibiotics were determined by the E test method.
Results: Thirty-six percent of isolates were resistant to more than one group of antibiotics. The rates of susceptible isolates were ciprofloxacin 75%, amikacin 73%, ceftazidime 65%, meropenem 63%, imipenem 63%, piperacillin/tazobactam 60%, cefoperazone/sulbactam 59%, cefepime 54% and tobramycin 44%. The majority of carbapenem resistant isolates were susceptible to ciprofloxacin and amikacin.
Conclusion: Ciprofloxacin seems to be the most active agent against P. aeruginosa followed by amikacin in our unit. The usefulness of combinations of these antibiotics and beta-lactams should be tested in treating multi-drug resistant P. aeruginosa.