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Rifabutin plus drug combination for adult patients with hospital‑acquired and ventilator‑associated pneumonia caused by carbapenem‑resistant Acinetobacter baumannii

Fast replyRegistered drugNo placebo
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What is this trial about?

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

A serious lung infection called hospital-acquired bacterial pneumonia, which can also occur as ventilator-associated bacterial pneumonia, is being studied. This infection happens after a stay in the hospital and is caused by a tough germ known as carbapenem-resistant Acinetobacter baumannii-calcoaceticus complex. The bacteria are resistant to many standard antibiotics, making treatment difficult and increasing the risk of illness or death.

The study compares two treatment approaches. One group receives a new drug identified as BV100 together with a low dose of polymyxin B, both given through an IV line. The other group receives the older antibiotic colistin combined with a higher dose of ampicillin/sulbactam, also by IV infusion. The purpose of the trial is to determine which combination works better and is safer for patients with this resistant infection. Participants are randomly assigned to one of the two groups, receive the medication for several days, and are then followed for about a month to see how they recover and to monitor any side effects.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Enrollment and randomization

    After signing the consent form, you are assigned to one of two treatment groups by a computer system. the assignment is called randomization and you will receive either the test regimen or the comparator regimen.

  2. Step 2

    Baseline assessments

    Before the first infusion, health care staff record your vital signs (blood pressure, heart rate, temperature), take blood samples for laboratory tests, and document any other medications you are using.

    These measurements serve as the reference point for evaluating your response to the study medication.

  3. Step 3

    Start of study medication

    The assigned medication is given by intravenous infusion each day.

    If you are in the test group, you receive bv100 (dose not disclosed) together with polymyxin b at a dose of 1 million iu (international units) per day.

    If you are in the comparator group, you receive colistin at a dose of 13.5 million iu per day together with ampicillin and sulbactam at a dose described as 9 df dosage form per day.

  4. Step 4

    Daily monitoring during treatment

    Each day you remain in the hospital, staff check your vital signs, repeat selected laboratory tests, and observe for any adverse events.

    The infusion is administered once daily according to the assigned dose.

  5. Step 5

    Scheduled efficacy assessments

    On day 3, day 5, and day 8 after the first infusion, you undergo clinical evaluation to determine whether the infection is improving. the same days may also include a microbiological sample to see if the bacteria are responding.

    These visits are called clinical cure and microbiological favorable assessment assessments.

  6. Step 6

    End of treatment evaluation

    When the study medication is stopped according to the protocol (often after 7‑14 days, depending on clinical judgment), a final assessment is performed. this includes a review of symptoms, vital signs, laboratory results, and any remaining adverse events.

  7. Step 7

    Test of cure visit

    Approximately 7‑14 days after the end of treatment, you return for a test of cure visit. the purpose is to confirm that the infection has resolved and no new problems have appeared.

  8. Step 8

    28‑day follow‑up

    28 days after the first infusion, a follow‑up contact is made to record survival status (all‑cause mortality) and any late occurring adverse events.

    This information is used for the primary endpoint of the study.

Who can join the trial?

10 criteria

  • Written informed consent must be signed before any study procedures; if the patient cannot sign, a legally authorized representative may provide consent.
  • Patient must be at least 18 years old and no older than 82 years old at the time of signing the consent.
  • Patient must have a confirmed diagnosis of hospital‑acquired bacterial pneumonia (HABP) or ventilator‑associated bacterial pneumonia (VABP) that requires treatment with intravenous (IV) antibiotics, as judged by the investigator.
  • There must be a high likelihood that the pneumonia is caused by carbapenem‑resistant Acinetobacter baumannii‑calcoaceticus complex (CRABC). This is shown by a rapid diagnostic test (RDT) performed on a respiratory sample (such as sputum, bronchoalveolar lavage, mini‑BAL, or endotracheal aspirate) collected before randomization, and the patient must either:
    • have received only a limited amount of potentially effective antibiotics against CRABC before the first study dose, or
    • show clinical failure (getting worse or not improving) after at least 48 hours of previous antibiotic treatment.
    • Patient must have a severity score indicating they are not too critically ill: an APACHE II score (a measure of acute illness) less than 30 **or** a quick Sequential Organ Failure Assessment (qSOFA) score of 2 or higher, measured within 24 hours of screening.
    • Women who could become pregnant must have a negative pregnancy test (urine or blood) before randomization and agree to use a highly effective method of contraception (condom, combined oral contraceptive, implant, injection, intrauterine device, or a partner who has had a vasectomy) from screening until at least 30 days after the last study dose. If only a combined oral contraceptive is used, an additional barrier method (such as a condom) is required.
    • Patient must meet the study’s definition of HABP or VABP as described in the protocol.
    • For enrollment in Part B (if not eligible for Part A), the patient can still participate if they have an infection caused by CRABC that is resistant to colistin or polymyxin B (defined by a minimum inhibitory concentration (MIC) ≥ 4 mg/L using a non‑agar method) and also meet one of the following:
      • have received only a limited amount of an antibiotic that the CRABC is susceptible to before the first study dose, or
      • show documented clinical failure after a specified period of treatment with colistin or polymyxin B.

Who cannot join the trial?

24 criteria

  • Cannot join if the infection is known to be resistant to colistin, if you cannot tolerate polymyxin drugs, or if you are taking another medicine that would stop you from receiving polymyxins.
  • Cannot join if liver enzymes called AST or ALT are more than three times the normal upper limit AND your total bilirubin (a substance that shows how well the liver works) is more than twice the normal level, or if you have severe chronic liver disease classified as Child‑Pugh Class C (advanced liver failure). Small temporary rises up to five times normal are allowed if they are caused by the infection being treated.
  • Cannot join if the doctor sees a serious heart problem on an ECG (electrocardiogram), such as new signs of reduced blood flow to the heart, a heart attack, dangerous fast heart rhythms, or very slow heart rate that cannot be fixed with a pacemaker or medication, or if you had severe heart failure (NYHA Class IV) within the past year.
  • Cannot join if a proper lung sample cannot be collected for testing (the sample must have very few squamous cells and enough white blood cells to be considered good).
  • Cannot join if your heart’s QT interval (a measure of electrical activity) corrected for heart rate (QTcF) is longer than 500 ms on two separate ECGs.
  • Cannot join if you had a stroke (either caused by a clot or bleeding) within the last 10 days, if doctors expect you will not survive 28 days after a stroke, or if you have a Glasgow Coma Scale score of 3 with no chance of improvement.
  • Cannot join if you are currently pregnant or breastfeeding.
  • Cannot join if you are already taking part in another clinical study, have finished another study within the past 30 days (or five half‑lives of the previous drug, whichever is longer), or are receiving other experimental medicines.
  • Cannot join if you have already received a set amount of other antibiotics that work against the bacteria being studied before the first dose of the trial drug, unless those antibiotics were for a different infection or were not effective against the study bacteria.
  • Cannot join if you need to keep taking medicines such as probenecid, methotrexate, ganciclovir, valproic acid or divalproex sodium during the trial.
  • Cannot join if you are allergic or possibly allergic to any of the following: polymyxin, rifabutin, colistin, ampicillin/sulbactam, meropenem or any of their inactive ingredients.
  • Cannot join if the medical team believes further treatment would be futile (no expected benefit) or if you live in a long‑term care facility and are receiving only comfort or palliative care.
  • Cannot join if you have a severe (grade 3 or higher) acute graft‑versus‑host disease, a condition that can occur after a transplant where the new immune cells attack the body.
  • Cannot join if you have another active lung infection that needs different antibiotics (for example, infections caused by Streptococcus pneumoniae, Staphylococcus aureus, viruses like influenza, or fungi like Aspergillus).
  • Cannot join if you have any of the following lung‑related problems: lung cancer blocking a airway, active tuberculosis, cystic fibrosis, fungal lung infection, lung abscess, fluid collection around the lung (pleural empyema) unless drained quickly, recent solid‑organ transplant (within 6 months), deep infections such as bone infection (osteomyelitis) or meningitis, severe heart valve infection (endocarditis), surgical wound infection needing more surgery, peritonitis (infection of the abdominal lining), an implanted device that cannot be removed and might be the source of the infection, nerve or muscle disease, HIV infection, or long‑term immune suppression from drugs or disease.
  • Cannot join if you have a blockage of a major airway (bronchial obstruction) or a history of pneumonia that occurred after such a blockage, unless you have chronic obstructive pulmonary disease (COPD) without these specific problems.
  • Cannot join if you are in sustained shock that requires strong medicines (vasopressors) to keep your blood pressure up, especially if the dose of these medicines is increasing or your blood lactate level is rising, unless the dose is very low and stable.
  • Cannot join if you have been diagnosed with ventilator‑associated tracheobronchitis, an infection of the airway that occurs while on a breathing machine.
  • Cannot join if, at the time of randomization or later during the study, you need or are likely to need additional systemic antibiotics that work against the study bacteria.
  • Cannot join if doctors expect you will not survive at least 72 hours or if you have a Do‑Not‑Resuscitate (DNR) order.
  • Cannot join if you have severe burns covering more than 40 % of your body.
  • Cannot join if you have a low white‑blood‑cell count (neutropenia) with fewer than 1500 neutrophils per microliter, either now or expected soon.
  • Cannot join if you have serious kidney disease, defined as an estimated glomerular filtration rate (eGFR) less than 30 mL/min/1.73 m², or if you are on peritoneal dialysis, hemodialysis, hemofiltration, or produce less than 20 mL of urine per hour over a full day.
  • Cannot join if you are unable or unwilling to follow the study procedures as judged by the investigator.
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Investigated drugs

  • BV100

    is an experimental medication being tested in this study. It is given through an IV drip and is intended to help fight infections caused by bacteria that are resistant to many antibiotics. In the trial, BV100 is combined with a low amount of another antibiotic to see if the combination works better than the standard treatment.

  • Polymyxin B

    is an older antibiotic that is used for serious infections caused by tough, resistant bacteria. In this study it is given in a small amount through an IV infusion and is used together with BV100. The goal is to see if this low dose can be effective while causing fewer side effects compared to higher doses.

  • Colistin

    is another strong antibiotic that is often used when infections do not respond to other medicines. It is given by IV infusion. In the trial, colistin is combined with a high dose of ampicillin/sulbactam and serves as the standard treatment that BV100 is being compared against.

  • Ampicillin and sulbactam

    is a combination of two medicines: ampicillin, which kills many types of bacteria, and sulbactam, which helps ampicillin work better against resistant strains. This combination is given by IV infusion, often with a local anesthetic called lidocaine to reduce pain from the infusion. In the study it is used at a high dose together with colistin as the active‑controlled therapy.

  • Rifabutin

    is an antibiotic that is sometimes used for infections caused by certain bacteria, such as tuberculosis. In this trial it is administered by IV infusion. Although it is not part of the main comparison, it is included as an additional therapy to evaluate its safety and effectiveness in patients with the same type of resistant pneumonia.

What is already known about the treatment

  • Ampicillin and Beta‑Lactamase Inhibitor

    This medication is given by intravenous infusion and comes as a mixture of ampicillin sodium, sulbactam sodium, and lidocaine hydrochloride. It is an approved and widely used antibiotic that treats many bacterial infections, including hospital‑acquired pneumonia. Ampicillin stops bacteria from building their cell wall, while sulbactam blocks enzymes that would destroy ampicillin, and lidocaine helps reduce any pain from the injection. It belongs to the penicillin class of antibiotics combined with a beta‑lactamase inhibitor.

  • Polymyxin B Sulfate

    Polymyxin B is supplied as a powder that is reconstituted for intravenous infusion. It is an older, still‑available drug used for serious infections caused by multidrug‑resistant Gram‑negative bacteria such as Acinetobacter. It works by attaching to the outer membrane of the bacteria and breaking it, which kills the organism. This drug is classified as a polymyxin antibiotic.

  • Colistim

    Colistin is administered by intravenous infusion in a ready‑to‑use solution. It is an approved treatment for life‑threatening infections caused by resistant Gram‑negative bacteria. Like Polymyxin B, it binds to the bacterial outer membrane and disrupts it, leading to bacterial death. It is also classified as a polymyxin antibiotic.

  • Rifabutin

    Rifabutin is given as an intravenous solution for infusion. It is an approved drug for tuberculosis and is sometimes used off‑label for other serious bacterial infections. It works by blocking an enzyme the bacteria need to make RNA, which stops their growth and eventually kills them. This medication belongs to the rifamycin class of antibiotics.

Investigated diseases

Carbapenem-resistant Acinetobacter baumannii‑calcoaceticus complex hospital‑acquired pneumonia - It is a lung infection that develops in patients after they are admitted to the hospital, often associated with the use of ventilators. The infection is caused by a strain of Acinetobacter baumannii‑calcoaceticus that does not respond to carbapenem antibiotics. Bacteria enter the airways, multiply, and trigger inflammation and fluid accumulation in the lungs. Early signs include cough, fever, and shortness of breath, which can become more intense as the infection spreads. The ongoing inflammation may extend to nearby lung tissue, leading to increasing difficulty in breathing.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-524092-23-00Protocol codeBV100-010Estimated enrolment380 patientsSponsorBioversys S.A.S.

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