Amendment 1: -The study was changed from a Phase 2 study to a Phase 2/3 study. -The primary objective was changed to the demonstration that ZTI-01 is non-inferior to PIP-TAZ in overall success in the treatment of cUTI or AP, and secondary objectives were added to include the comparison of the clinical cure rates and microbiologic eradication of the 2 treatment groups. -The population for the study was increased from approximately 200 patients to 460 patients to increase the power of the study. -Elevated WBC count was eliminated as a sign or symptom of cUTI or AP. -The duration of contraception requirements for study participants was shortened based on toxicity studies. -The threshold for the thrombocytopenia exclusion criterion was lowered from 60,000 platelets/mm3 to 50,000 platelets/mm3. -The 4 g ZTI-01 treatment group was eliminated, and the ratio of patients randomized to the 2 treatment groups was changed to 1:1. -The duration of treatment was changed to 7 days for all patients unless deemed a treatment failure, and the TOC Visit was changed to Day 12 (+2 days). -A DMC was added to assess safety and evaluability during the study. -Outcome definitions were clarified. -The secondary efficacy analyses at the LFU Visit were made additional efficacy analyses to support the primary and secondary outcomes. -The statistical efficacy analyses were updated to reflect the changes in the primary and secondary objectives and efficacy analyses. -The sample size rationale was updated to reflect the increased sample size and power of the study. -The number of sites was increased from 60 to 100 to 115. -An unblinded site monitor was added to ensure the blind was maintained throughout the study. -Infusion of 5% dextrose to maintain the blind was added in situations where patients may not be safely administered free WFI. -The 12-lead ECG in triplicate was changed to a single reading. -Changes were also made for clarity and/or consistency.

Amendment 2: -Changes were made to inclusion and exclusion criteria; -Procedures for dosing in patients with renal insufficiency were specified; -The duration of treatment was changed to 7 to 14 days, the TOC Visit was changed to Day 19, and the LFU Visit was changed to Day 26; -Urine isolate growth criteria was changed to >1x10^3 CFU/mL for laboratory analysis; -Baseline urine and blood samples submitted to the central laboratory were specified; -Patient treatment in cases of non-susceptibility to study drug was provided; -Determination of serum creatinine within 24 hours of first dose of study drug was specified; -Proportion of patients with a response of clinical cure in the MITT and m-MITT -Populations at Day 5 were added as an additional efficacy endpoint; -Per-pathogen microbiologic eradication rate in the m-MITT and ME-TOC -Populations at the TOC Visit was added as an additional efficacy endpoint; -Treatment failure, per-patient clinical improvement, and recommended minimum duration for clinical evaluation were added to premature discontinuation of study drug; -Staff responsible for documenting and maintaining logs for study drug receipt, storage, preparation, and dispensing were identified; -Procedures for study drugs that experienced a temperature excursion during shipment were provided; -Screening and randomization procedures were clarified, and determination of serum creatinine results within 24 hours of first dose of study drug was added to procedures; -Daily determination of CrCl and daily assessment of vital signs were added to procedures performed during the Treatment Period; -Definition of an adverse event was clarified; -Determination of whether an adverse event was related/not related to study drug was clarified; -PIP-TAZ vial formulation for use in the United States was added; -Changes were also made for clarity and/or consistency.