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Comparing piperacillin-tazobactam and meropenem for treating bloodstream infections caused by cephalosporin-resistant bacteria in adult patients

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study focuses on treating bloodstream infections (bacteremia) caused by specific bacteria that are resistant to certain antibiotics. The research compares two different antibiotic treatments: piperacillin-tazobactam and meropenem. The bacteria being studied include several types that commonly cause infections in the blood, such as Escherichia coli, Klebsiella species, and other related bacteria that have developed resistance to commonly used antibiotics.

The purpose of this research is to determine if piperacillin-tazobactam works as effectively as meropenem in treating these resistant blood infections. Both medications are given through an intravenous infusion, which means they are administered directly into the bloodstream. Piperacillin-tazobactam can be given up to 18 grams per day, while meropenem can be given up to 3 grams per day.

During the study, patients will receive one of these two antibiotic treatments. The doctors will monitor how well the infection responds to treatment, checking for signs of improvement or failure over several months. They will also watch for any side effects and track whether the infection returns. The study will look at various outcomes, including how long patients need to stay in the hospital and whether they develop any new infections during the treatment period.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial blood test confirmation

    Your blood test has shown an infection caused by specific bacteria that are resistant to some antibiotics but can be treated with either of the study medications.

    The infection type being treated is called bacteremia, which means bacteria are present in your blood.

  2. Step 2

    Random assignment to treatment group

    You will be randomly assigned to receive one of two medications:

    - Meropenem: given as a 2g solution through injection or infusion

    - Piperacillin/Tazobactam: given as a 2g/0.25g solution through infusion

  3. Step 3

    Treatment period

    You will receive the assigned medication for at least 7 days

    Your doctor will monitor your response to treatment and may adjust the treatment if necessary

  4. Step 4

    Follow-up evaluations

    Your health will be monitored at specific intervals: 7, 14, 30, and 90 days after starting treatment

    During these check-ups, you will be evaluated for:

    - Response to treatment

    - Any new infections

    - Possible side effects

    - Development of antibiotic resistance

  5. Step 5

    Extended monitoring

    Your health will continue to be monitored for up to 90 days to check for:

    - Any return of infection

    - New infections

    - Hospital readmissions if needed

    - Total days of antibiotic use

    The study will record any hospital stays required during this period

Who can join the trial?

14 criteria

  • Must be 18 years of age or older
  • Must have a newly diagnosed bloodstream infection (infection present in the blood) caused by specific bacteria:
    • E. coli
    • Klebsiella species
    • Serratia marcescens
    • Providencia species
    • Morganella morganii
    • Citrobacter freundii
    • Enterobacter species
    • The bacteria causing the infection must be:
      • Resistant to certain antibiotics called third-generation cephalosporins (specifically ceftriaxone and ceftazidime)
      • Able to be treated with antibiotics called PTZ and meropenem
      • Can have an infection that started either:
        • In the community (outside the hospital)
        • In the hospital
        • Can participate if other harmless skin bacteria are found in the blood test along with the infection-causing bacteria
        • Both men and women can participate

Who cannot join the trial?

10 criteria

  • Patient is under 18 years of age
  • Patient has a known severe allergy to meropenem or piperacillin-tazobactam (antibiotics used in the study)
  • Patient has a severe kidney impairment requiring dialysis
  • Patient is pregnant or breastfeeding
  • Patient has other types of bacteria in the blood than those specified for the study (E. coli, Klebsiella, Serratia, Providencia, Morganella, Citrobacter, or Enterobacter)
  • Patient has received more than 24 hours of effective antibiotic treatment before enrollment
  • Patient has a severe immune system disorder
  • Patient is participating in another clinical trial
  • Patient is unable to provide informed consent
  • Patient has a condition that would make it unsafe to participate in the study
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Investigated drugs

Piperacillin/Tazobactam (PTZ) is an antibiotic combination medication used to treat serious bacterial infections. It works by stopping the growth of bacteria. This medication combines two different antibiotics that work together to fight infections, particularly those caused by resistant bacteria. Meropenem is a powerful antibiotic belonging to the carbapenem class. It is used to treat severe bacterial infections and is particularly effective against a wide range of bacteria, including those that have become resistant to other antibiotics. It works by preventing bacteria from building their cell walls, which leads to their death. Both medications are given intravenously (through a vein) and are commonly used to treat serious bloodstream infections caused by certain types of bacteria that have become resistant to other antibiotics.

What is already known about the treatment

  • Piperacillin/Tazobactam

    An injectable antibiotic combination medication that consists of piperacillin (a penicillin antibiotic) and tazobactam (a beta-lactamase inhibitor). This medication works by preventing bacteria from building their cell walls while also blocking their resistance mechanisms, making it effective against many types of bacterial infections, particularly those caused by resistant organisms. It is commonly used to treat severe infections including bacteremia (bloodstream infections) and is administered intravenously in hospital settings.

  • Meropenem

    A broad-spectrum carbapenem antibiotic administered through intravenous injection that is particularly effective against serious bacterial infections. It works by interfering with bacterial cell wall synthesis, leading to cell death, and is especially valuable in treating infections caused by resistant organisms including Extended-Spectrum Beta-Lactamase (ESBL) producing bacteria. This antibiotic is often reserved for severe infections and is considered one of the last-resort antibiotics in many healthcare settings due to its powerful action against resistant bacteria.

Investigated diseases

  • Bacteremia

    A condition where bacteria are present in the bloodstream, causing a blood infection. The bacteria multiply in the blood, spreading throughout the body via the circulatory system. This condition typically develops when bacteria from another infection site enter the bloodstream. Bacteremia can cause various symptoms including fever, chills, and rapid breathing. The condition may affect different body systems as the bacteria travel through the blood vessels.

  • Clostridium difficile infection

    An infection that affects the large intestine, causing inflammation of the colon. The condition typically develops after the use of antibiotics, which can disrupt the normal balance of bacteria in the gut. The infection leads to symptoms such as diarrhea, abdominal pain, and fever. The bacteria produce toxins that damage the lining of the intestine.

  • Enterobacteriaceae infections

    Infections caused by a family of bacteria that commonly reside in the intestines. These bacteria can cause various types of infections when they spread to other parts of the body. The infections may affect different organs and systems, particularly the urinary tract, respiratory system, or bloodstream. Common bacteria in this family include Escherichia coli (E. coli), Klebsiella, and Enterobacter species.

Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-518583-13-00Protocol codePETERPENEstimated enrolment490 patientsSponsorAzienda Ospedaliero Universitaria Di Modena

sourced from the EU Clinical Trials Register and site verification

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).