MK-7625A Versus Meropenem in Pediatric Participants With Complicated Urinary Tract Infection (cUTI) (MK-7625A-034)

Inclusion Criteria: * Has a legally acceptable representative who provides documented informed consent / assent for the trial. * Ages from birth (defined as \>32 weeks gestational age and ≥7 days postnatal) to \<18 years of age. * Requires IV antibacterial therapy for the treatment of cUTI. * Have a pretreatment baseline urine culture specimen obtained within 48 hours before the start of administration of the first dose of study treatment and preferably prior to administration of any potentially therapeutic antibiotics. * Has pyuria. * Has clinical signs and/or symptoms of cUTI at the Screening Visit. * Is not of reproductive potential; but if of reproductive potential agrees to avoid becoming pregnant or impregnating a partner during screening, while receiving study treatment and for at least 30 days after the last dose of study treatment. * Female of reproductive potential is not pregnant, and not planning to become pregnant within 30 days of the last day of treatment administration; and is nonlactating. Exclusion Criteria: * Is currently participating in or has participated in an interventional clinical trial with an investigational compound or device within 30 days prior to the first dose of study treatment in this current trial. * Has previously participated in any trial of ceftolozane or ceftolozane/tazobactam or has enrolled previously in the current trial and been discontinued. * Has a history of any moderate or severe hypersensitivity (e.g.anaphylaxis), allergic reaction, or other contraindication to any of the following: β-lactam antibiotics (e.g, penicillins, cephalosporins, and carbapenems), β-lactamase inhibitors (e.g. tazobactam, sulbactam, clavulanic acid, avibactam), or metronidazole. * Has a history of a cUTI within the past 1 year prior to randomization known to be caused by a pathogen resistant to either IV study treatment. * Has a concomitant infection at the time of randomization that requires nonstudy systemic antibacterial therapy in addition to IV study treatment or oral step -down therapy. * Has received potentially therapeutic antibacterial therapy for a duration more than 24 hours during the 48 hours preceding the first dose of study treatment. * Has any of the following: a) intractable UTI or pyelonephritis infection at baseline that the Investigator anticipates would require more than 14 days of study treatment; b) confirmed fungal urinary tract infection at time of randomization; c) permanent indwelling bladder catheter or instrumentation including nephrostomy; d) current urinary catheter that is not scheduled to be removed before the end of all study treatment; e) complete, permanent obstruction of the urinary tract; f) suspected or confirmed perinephric or intrarenal abscess; g) documented ileal loop reflux; h) suspected or confirmed prostatitis, urethritis, or epididymitis; i) trauma to pelvis/urinary tract. * Has moderate or severe impairment of renal function. * Has a seizure disorder or is anticipated to be treated with divalproex sodium or valproic acid during the course of study treatment. * Is receiving, or is expected to receive, any prohibited medications. * Has any rapidly progressing disease or immediately life-threatening illness, including acute hepatic failure, respiratory failure, or septic shock. * Has an immunocompromising condition. * Has a history of malignancy ≤5 years prior to signing informed consent. * Is planning to receive suppressive/prophylactic antibiotics with gram-negative activity after completion of study treatment.