Background: Catheter associated urinary tract infection is considered as the commonest complication of indwelling catheter. Chronic indwelling catheters are an important reservoir of different multiresistant gram-negative organisms as Pseudomonas aeruginosa. Methodology: Our study was carried out on patient with CAUTI who were admitted to Urology Department at Tanta University Hospital. Pseudomonas aeruginosa isolates that were resistant to meropenem were subjected to phenotypic detection of efflux pump mechanism by CCCP test and genotypic detection of efflux pump gene by PCR. Results: P- aeruginosa was isolated from 14.6% of CAUTI. Meropenem resistance was found in 19.6% of isolates. We found 100% correlation between phenotypic and genotypic detection method as regard mex A gene.