Used primarily in medical and research settings to treat infections caused by Gram-negative bacteria, especially Pseudomonas aeruginosa. It is effective in hospital-acquired infections such as urinary tract infections, respiratory tract infections, and septicemia. Due to its stability against many beta-lactamases, it is valuable in treating infections resistant to other penicillins and cephalosporins. Also used in microbiology laboratories as a selective agent in culture media to isolate specific pathogens.