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Efficacy of Ceftolozane/Tazobactam versus Levofloxacin in the Treatment of Complicated Urinary Tract Infections (cUTI) caused by Levofloxacin-resistant Pathogens: Results from the ASPECT-cUTI Trial

Session: Poster Abstract Session: UTIs: Management and Issues in DrugóResistance
Friday, October 10, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC
Background: Ceftolozane/tazobactam demonstrates excellent activity in vitro against Gram-negative pathogens, including extended spectrum β-lactamase‒producing Enterobacteriaceae and multidrug-resistant Pseudomonas aeruginosa.  The efficacy of ceftolozane/tazobactam in the subset of patients with cUTI, including pyelonephritis, caused by levofloxacin (LVX)-resistant pathogens was examined from pooled efficacy data of 2 Phase 3, randomized, controlled, double-blind trials (NCT01345929 and NCT01345955).

Methods: Hospitalized patients ≥18 years old with pyuria and clinical symptoms of cUTI were randomized to either intravenous ceftolozane/tazobactam 1.5 g every 8 hours or intravenous LVX 750 mg/d for 7 days, prior to availability of susceptibility data. Primary outcome was the composite microbiological eradication and clinical cure (composite cure) rate at the test-of-cure (TOC) visit 5-9 days after the end of therapy in the microbiological modified intent-to-treat (mMITT) and microbiologically evaluable (ME) populations. 

Results: A total of 1083 patients were enrolled, 800 were included in the mMITT population, and 212 had LVX‑resistant baseline uropathogens; 176/212 were susceptible to ceftolozane/tazobactam.  Ceftolozane/tazobactam demonstrated significantly higher composite cure rates and per‑pathogen microbiological eradication rates vs LVX in the mMITT and ME populations (Table).

Outcomes in the LVX‑resistant Population at TOC




% (n/N)


% (n/N)


% (95% Confidence Interval)

Composite Cure Rate


60.0 (60/100)

39.3 (44/112)

20.7 (7.23 to 33.17)


64.0 (57/89)

43.4 (43/99)

20.6 (6.33 to 33.72)

Per-pathogen Microbiological Eradication Rate







71.4 (55/77)

45.2 (38/84)

26.2 (10.96 to 39.72)

            Escherichia coli


72.9 (43/59)

44.1 (30/68)

28.8 (11.59 to 43.55)

            Klebsiella pneumoniae


81.8 (9/11)

30.0 (3/10)

51.8 (9.50 to 75.05)

      P. aeruginosa


100.0 (3/3)

37.5 (3/8)

62.5 (-2.09 to 86.32)

Conclusion: Ceftolozane/tazobactam demonstrated superior composite cure rates vs LVX in cUTI caused by LVX-resistant pathogens. Ceftolozane/tazobactam may offer an alternative treatment for cUTI in settings of increasing fluoroquinolone resistance among common uropathogens.

George Sakoulas, MD1, Obiamiwe Umeh, MD, MSc2, Jennifer Huntington, PharmD2, Daniel Cloutier, PharmD2, Judith Steenbergen, PhD2, Guojun Yuan, PhD2, Minjung Yoon, MPH2 and Ellie Goldstein, MD, FIDSA, FSHEA3, (1)Department of Pediatrics, University of California San Diego School of Medicine, San Diego, CA, (2)Cubist Pharmaceuticals, Lexington, MA, (3)RM Alden Research Laboratory, Santa Monica, CA


G. Sakoulas, Cubist Pharmaceuticals: Consultant and Speaker's Bureau, Consulting fee and Speaker honorarium

O. Umeh, Cubist Pharmaceuticals: Employee and Shareholder, Salary

J. Huntington, Cubist Pharmaceuticals: Employee and Shareholder, Salary

D. Cloutier, Cubist Pharmaceuticals: Employee and Shareholder, Salary

J. Steenbergen, Cubist Pharmaceuticals: Employee and Shareholder, Salary

G. Yuan, Cubist Pharmaceuticals: Employee, Salary

M. Yoon, Cubist Pharmaceuticals: Employee, Salary

E. Goldstein, Cubist Pharmaceuticals: Grant Investigator, Scientific Advisor and Speaker's Bureau, Grant recipient

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