This is a study in adult subjects with complicated urinary tract infection (cUTI) comparing treatment with intravenous (IV) coadministered ceftaroline fosamil and NXL104 versus treatment with IV doripenem.

Inclusion Criteria:

Subjects must meet the following inclusion criteria:

• Have pyuria (white blood cells in the urine)
• Clinical signs and/or symptoms of cUTI (including acute pyelonephritis)
• Have a pretreatment baseline urine culture specimen
• The subject's infection would require initial treatment with IV antibiotics
• The subject must require initial hospitalization to manage the cUTI by the standard of care.

Exclusion Criteria:

Subjects must NOT meet any of the following exclusion criteria:

• History of any hypersensitivity or allergic reaction to any β-lactam (eg, cephalosporins, penicillins, carbapenems)
• Confirmed fungal urinary tract infection
• Intractable UTI anticipated to require more than 10 days of study drug therapy
• Complete, permanent obstruction of the urinary tract\
• Permanent indwelling bladder catheter or instrumentation (including nephrostomy) or current urinary catheter that will not be removed during IV study drug administration
• Suspected or confirmed perinephric or intrarenal abscess
• Suspected or confirmed prostatitis
• Ileal loops or vesico-ureteral reflux
• Impairment of renal function including a calculated CrCl of < 30 mL/min, requirement for peritoneal dialysis, hemodialysis or hemofiltration, or oliguria
• Renal transplantation
• Life expectancy less than 3 months
• Evidence of significant hepatic, hematological, or immunologic disease or dysfunction
• Past or current history of epilepsy or seizure disorder
• Women who are pregnant or nursing