Relebactam is used in combination with other antibiotics, particularly imipenem and cilastatin, to treat complicated infections caused by multidrug-resistant Gram-negative bacteria. It works by inhibiting certain beta-lactamase enzymes that bacteria produce to resist antibiotics, thereby restoring the effectiveness of the partnered antibiotic. This combination is especially valuable in treating hospital-acquired pneumonia, including ventilator-associated pneumonia, and complicated intra-abdominal infections. Relebactam enhances the spectrum of activity against problematic pathogens such as Pseudomonas aeruginosa and some Enterobacterales that are otherwise difficult to treat due to their resistance mechanisms. Its use is typically reserved for serious infections where few other treatment options are effective.