Safety and Efficacy of IV CXA-101 and IV Ceftazidime in Patients With Complicated Urinary Tract Infections

Inclusion Criteria: 1. Males and females 18 to 90 years of age, inclusive. 2. Pyuria (white blood cell \[WBC\] count \> 10/µL in unspun urine or ≥ 10 per high power field in spun urine) 3. Clinical signs and/or symptoms of cUTI, either of: a. Pyelonephritis, as indicated by both of the following: i. Fever (oral temperature ≥ 37.8°C); ii. Flank pain or costovertebral angle tenderness; OR b. Complicated lower UTI, as indicated by both of the following: i. At least one of the following new or worsening symptoms: * Dysuria; * Frequency; * Suprapubic pain; * Urgency ii. At least one of the following complicating factors: * Male gender; * Current bladder instrumentation or indwelling urinary catheter that is expected to be removed during the course of IV study drug administration; * Obstructive uropathy that is expected to be medically or surgically treated during the course of IV study drug administration; * Urogenital surgery within 7 days preceding administration of the first dose of study drug; * Functional or anatomical abnormality of the urogenital tract including anatomic malformations or neurogenic bladder with voiding disturbance of at least 100 mL residual urine. Exclusion Criteria 1. Documented history of any hypersensitivity or allergic reaction to any β-lactam antibacterial 2. Concomitant infection requiring systemic antibacterial therapy in addition to IV study drug therapy at the time of randomization. Drugs with only gram-positive activity (e.g. vancomycin, linezolid) are allowed 3. Complete, permanent obstruction of the urinary tract 4. Confirmed (at time of randomization) fungal urinary tract infection (with ≥ 103 fungal CFU/mL) 5. Suspected or confirmed perinephric or intrarenal abscess 6. Suspected or confirmed prostatitis 7. Known ileal loop or vesico-ureteral reflux 8. Women who are pregnant or nursing