Efficacy and Safety of Cefepime/Nacubactam or Aztreonam/Nacubactam Compared to Imipenem/Cilastatin in Subjects With Complicated Urinary Tract Infections or Acute Uncomplicated Pyelonephritis (Integral-1)

Inclusion Criteria: Male or female patients at least18 years of age (or age of legal consent, whichever is older) at the time of obtaining informed consent and who can be hospitalized throughout the Treatment Period; Weight at most 140 kg; Expectation, in the opinion of the Investigator, that the patient's cUTI or AP will require treatment with at least 5 days of IV antibiotics; Exclusion Criteria: Has a known imipenem- and/or meropenem-resistant Gram-negative uropathogen (at least 10^5 CFU/mL), isolated from study-qualifying urine culture; Note: If after randomization the susceptibility testing indicates resistance to imipenem and/or meropenem, the patient may remain on the study drug at the Investigator's discretion. Has known or suspected single or concurrent infection with Acinetobacter spp. or other organisms that are not adequately covered by the study drug (eg, concurrent viral, mycobacterial, or fungal infection) and needs to be managed with other anti-infectives; Note: Patients with qualifying pathogen coinfected with a Gram-positive pathogen may be administered narrow spectrum, open-label glycopeptide (eg, vancomycin), oxazolidinone (eg, linezolid), or daptomycin concomitantly with the study drug at the Investigator's discretion. Has only a known Gram-positive primary uropathogen (at least 10^5 CFU/mL), isolated from study qualifying urine culture;