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RCT Meropenem vs Piperacillin-Tazobactam for Definitive Treatment of BSI's Due to Ceftriaxone Non-susceptible Escherichia Coli and Klebsiella Spp. (MERINO)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT02176122
Recruitment Status : Terminated (Secondary to third interim analysis by the study DSMB.)
First Posted : June 26, 2014
Last Update Posted : November 27, 2017
International Society of Chemotherapy
Australian Society for Antimicrobials
Queensland Clinical Trials & Biostatistics Centre
Australasian Society for Infectious Diseases
Information provided by (Responsible Party):
Professor David L. Paterson, The University of Queensland

Brief Summary:

No randomized controlled trials (RCTs) have yet been performed comparing different treatment options for AmpC or ESBL-producing Enterobacteriaceae. During the last 10 years we have seen an exponentially increasing rate of carbapenem resistance worldwide, including Australia and New Zealand. The investigators urgently need data from well-designed RCTs to guide clinicians in the treatment of antibiotic resistant Gram-negative infections. The investigators face a situation where a commonly used antibiotic for these infections (meropenem) may be driving carbapenem resistance. For this reason, the investigators are seeking to compare a carbapenem-sparing regimen with a carbapenem for the treatment of these infections. Formal evaluation of safety and efficacy of generic antibiotics in the treatment of infection is of immense clinical and public health importance, and no formal trial has yet been conducted to address these issues. The international collaboration between teams of clinician researchers, some of whom are leaders in their field, makes it highly likely that the outcomes of this trial will have a significant impact on clinical practice.

The investigators' hypothesis is that piperacillin/tazobactam (a carbapenem-sparing regimen) is non-inferior to meropenem (a widely used carbapenem) for the definitive treatment of bloodstream infections due to third-generation cephalosporin non-susceptible E. coli or Klebsiella species.

Condition or disease Intervention/treatment Phase
Bloodstream Infections Drug: Meropenem Drug: Piperacillin-tazobactam combination product Phase 4

Detailed Description:

Escherichia coli and Klebsiella spp. are common causes of bacteraemia, and may acquire genes encoding extended-spectrum beta-lactamases (ESBLs) or AmpC beta-lactamases (1). ESBL or AmpC producers are typically resistant to third generation cephalosporins such as ceftriaxone, but susceptible to carbapenems (1). Observational studies have been performed evaluating antibiotic choices for ESBL producers (2-9). In no study has the outcome of treatment for serious infections for ESBL producers been significantly surpassed by carbapenems (2-9).

Despite the potential advantages of carbapenems for treatment of ceftriaxone non-susceptible organisms, widespread use of carbapenems may cause selection pressure leading to carbapenem-resistant organisms. This is a significant issue since carbapenem-resistant organisms are treated with "last-line" antibiotics such as colistin. Some new beta-lactam antibiotics and beta-lactamase inhibitors, which are active against ESBL, AmpC and some carbapenemase producing organisms, are in advanced clinical development (10). However, these antibiotics are likely to be expensive and may best be held in reserve for infections where there are no alternatives. Therefore, we see a need for establishing the efficacy of a generically available alternative to carbapenems for serious infections.

The susceptibility of ESBL producers and AmpC producers to piperacillin/tazobactam is less predictable than that of carbapenems. By definition, ESBLs are inhibited by beta-lactamase inhibitors such as tazobactam (1). However, E. coli or Klebsiella may produce multiple beta-lactamase types some of which are resistant to inhibition by tazobactam. Additionally, in some cases outer membrane protein loss may contribute to resistance to tazobactam. By definition, AmpC is not inhibited by beta-lactamase inhibitors such as tazobactam. However, despite these limitations, approximately 50% or more of ceftriaxone non-susceptible E. coli or Klebsiellae remain susceptible in vitro to piperacillin/tazobactam (1).

No randomised controlled trials have yet been performed comparing different treatment options for ceftriaxone resistant Enterobacteriaceae. The largest observational study with an analysis by treatment outcome was published in February 2012 by Rodriguez-Bano and colleagues (9). They performed a post-hoc analysis of six published cohorts of patients with bacteraemia due to ESBL producing E. coli. Two nonmutually exclusive cohorts (empirical therapy and definitive therapy) were constructed and analysed separately. In both cohorts, carbapenems were not superior to beta-lactam/beta-lactamase inhibitor combinations (BLBLIC). Specifically, in the definitive therapy cohort, mortality rates at 30 days were not significantly different - 9.3% for those who received a BLBLIC and 16.7% for those who received a carbapenem (p>0.20) (9).

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 391 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Randomized Controlled Trial of Meropenem Versus Piperacillin-Tazobactam for Definitive Treatment of Bloodstream Infections Due to Ceftriaxone Non-susceptible E. Coli and Klebsiella Species.
Study Start Date : February 2014
Actual Primary Completion Date : July 7, 2017
Actual Study Completion Date : August 7, 2017

Arm Intervention/treatment
Active Comparator: Meropenem
Meropenem 1g adm every 8 hours IV up to study day 4.
Drug: Meropenem
Meropenem is a carbapenem anti-bacterial used for the treatment of serious infections in patients.
Other Names:
  • Merrem
  • Meronem

Experimental: Piperacillin-tazobactam combination product
Piperacillin/tazobactam 4.5g adm every 6 hours IV up to study day 4.
Drug: Piperacillin-tazobactam combination product
Piperacillin-tazobactam is used for the treatment of patients with systemic and/or local bacterial infections.
Other Names:
  • Zosyn
  • Tazocin

Primary Outcome Measures :
  1. Mortality at 30 days [ Time Frame: 30 days ]
    To compare the 30-day mortality post bloodstream infection of piperacillin/tazobactam and meropenem.

Secondary Outcome Measures :
  1. Time to clinical and microbiologic resolution of infection [ Time Frame: on or before study day 4 ]
    defined as number of days from randomisation to resolution of fever (temperature > 38.0o C) and leucocytosis (white blood cell count >12x109/L) PLUS sterilisation of blood cultures.

  2. Clinical and microbiologic success [ Time Frame: day 4 ]
    defined as survival PLUS resolution of fever and leucocytosis PLUS sterilisation of blood cultures

  3. Microbiologic resolution of infection [ Time Frame: day 4 ]
    defined as sterility of blood cultures collected on or before day 4

  4. Microbiologic relapse [ Time Frame: day 30 ]
    defined as growth of a meropenem resistant Gram negative bacillus from any clinical specimen collected or a positive stool test (according to local lab diagnostic procedures) for C. difficile, from day 4 of study drug administration to day 30

  5. Superinfection with a carbapenem or piperacillin-tazobactam resistant organism or Clostridium Difficile [ Time Frame: day 30 ]
    To compare the risk of superinfection with a carbapenem resistant organism with each regimen.

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Bloodstream infection with E. coli or Klebsiella spp. with proven non-susceptibility to third generation cephalosporins and susceptibility to meropenem and piperacillin-tazobactam from at least one blood culture draw. This will be determined in accordance with laboratory methods and susceptibility breakpoints defined by EUCAST standards (www. Bacterial identification to species level will be performed using standard laboratory methods (e.g. MALDI-TOF) and susceptibility testing (e.g. Vitek2)
  • No more than 72 hours has elapsed since the first positive blood culture collection.
  • Patient is aged 18 years and over
  • The patient or approved proxy is able to provide informed consent.

Exclusion Criteria:

  • Patient not expected to survive more than 4 days
  • Patient allergic to a penicillin or a carbapenem
  • Patient with significant polymicrobial bacteraemia (that is, a Gram positive skin contaminant in one set of blood cultures is not regarded as significant polymicrobial bacteraemia).
  • Treatment is not with the intent to cure the infection (that is, palliative care is an exclusion).
  • Pregnancy or breast-feeding.
  • Use of concomitant antimicrobials in the first 4 days after enrolment with known activity against Gram-negative bacilli (except trimethoprim/sulfamethoxazole may be continued as Pneumocystis prophylaxis).

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT02176122

Show Show 31 study locations
Sponsors and Collaborators
The University of Queensland
International Society of Chemotherapy
Australian Society for Antimicrobials
Queensland Clinical Trials & Biostatistics Centre
Australasian Society for Infectious Diseases
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Principal Investigator: David L Paterson, MD, PhD UQCCR, RBWH
Publications automatically indexed to this study by Identifier (NCT Number):
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Responsible Party: Professor David L. Paterson, Professor of Medicine, Infectious Diseases Consultant and Clinical Microbiologist, The University of Queensland Identifier: NCT02176122    
Other Study ID Numbers: ACTRN12613000532707
First Posted: June 26, 2014    Key Record Dates
Last Update Posted: November 27, 2017
Last Verified: November 2017
Additional relevant MeSH terms:
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Systemic Inflammatory Response Syndrome
Pathologic Processes
Piperacillin, Tazobactam Drug Combination
Anti-Bacterial Agents
Anti-Infective Agents
beta-Lactamase Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action