In strains from hospital-acquired infections, high correlation percentages ranging from 89.5% (60/67) to 100% (67/67) were detected for adhesion (pilA), biofilm formation (ndvB), outer membrane protein (oprL and oprI), elastase (lasA and las B), alkaline protease (apr), alginate pseudocapsule (algD), chaperone (groEL), epoxide hydrolase (cif), and efflux pump systems (mexB, mexF, mexY, and mexZ) genes with the resistance phenotype to beta-lactams (AM, CB, CF, and CFX) and trimethoprim/sulfamethoxazole (SXT). This evidence concerns the gene OPRL1 and nosocomial infection.