Switching to oral antibiotics for uncomplicated Gram-negative bacteraemia

Early Oral Step-down Antibiotic Therapy Versus Continuing Intravenous Therapy for Uncomplicated Gram-negative Bacteraemia (the INVEST Trial)

Phase 4 Interventional Tan Tock Seng Hospital · NCT05199324

This study tests if switching from IV antibiotics to oral antibiotics within 72 hours can help adults with uncomplicated Gram-negative bacteraemia just as well as sticking with IV treatment.

Quick facts

PhasePhase 4
Study typeInterventional
Enrollment720 (estimated)
Ages18 Years and up
SexAll
SponsorTan Tock Seng Hospital Academic / other
Drugs / interventionschemotherapy
Locations1 site (Singapore, Singapore)
Trial IDNCT05199324 on ClinicalTrials.gov

What this trial studies

This clinical trial evaluates the effectiveness and economic impact of switching from intravenous (IV) antibiotics to oral antibiotics within 72 hours for patients with uncomplicated Gram-negative bacteraemia. It is a multicentre, randomised controlled trial that compares early oral step-down therapy using fluoroquinolones or trimethoprim-sulfamethoxazole against continued IV therapy. Participants must be clinically stable and over 18 years old, and the study aims to determine if early oral treatment is as effective as standard IV care. The trial will also assess the safety and feasibility of this approach in a real-world clinical setting.

Who should consider this trial

Good fit: Ideal candidates are clinically stable adults over 18 years old with uncomplicated Gram-negative bacteraemia.

Not a fit: Patients with complicated infections or those requiring surgical intervention will not benefit from this study.

Why it matters

Potential benefit: If successful, this approach could reduce hospital stays and healthcare costs while maintaining effective treatment for patients.

How similar studies have performed: Other studies have shown promise in transitioning to oral antibiotics for similar conditions, but this specific approach is being tested for the first time.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

1. One or more set(s) of blood cultures positive for Gram-negative bacteria (GNB) associated with evidence of infection
2. Able to be randomised within 72 hours of index blood culture collection
3. Age ≥18 years (≥21 in Singapore)
4. Latest Pitt bacteraemia score \<4
5. Patient or legal representative is able to provide informed consent

Exclusion Criteria:

1. Established uncontrolled focus of infection, including but not limited to:

   * Undrained abdominal abscess, deep seated intra-abdominal infection and other unresolved abdominal sources requiring surgical intervention
   * Central nervous system abscess (patients with focal neurology should have cranial CT prior to enrolment)
   * Undrained moderate-to-severe hydronephrosis
2. Complicated infections, including but not limited to:

   * Necrotising fasciitis
   * Empyema
   * Central nervous system infections and meningitis
   * Endocarditis / endovascular infections
3. Septic shock as defined by systolic blood pressure \<90 or mean arterial pressure \<70 mmHg despite adequate fluid resuscitation or need for inotropic/vasopressor support
4. Polymicrobial bacteraemia involving Gram-positive pathogens or anaerobes (defined as either growth of 2 or more different microorganism species in the same blood culture, or growth of different species in 2 or more separate blood cultures within the same episode \[\<48 hours\] and with clinical or microbiological evidence of the same source)
5. Bacteraemia is due to a vascular catheter or intravascular materials (e.g. pacing wire, vascular graft) that cannot be removed
6. Specific Gram-negative pathogens that cannot be effectively treated with fluoroquinolones or trimethoprim-sulfamethoxazole, including but not limited to, Burkholderia spp. and Brucella spp.
7. Index GNB with resistance to fluoroquinolones AND trimethoprim-sulfamethoxazole
8. Hypersensitivity to fluoroquinolones AND sulphur drugs as defined by history of rash, urticaria, angioedema, bronchospasm, circulatory collapse or significant adverse reaction following prior administration
9. Unable to consume or absorb oral medications for any reason or unsuitable for ongoing IV therapy (e.g. no intravenous access)
10. Severely immunocompromised in the opinion of the treating doctor, including but not limited to, medical conditions such as:

    * Active leukaemia or lymphoma
    * Aplastic anaemia
    * Bone marrow transplant within two years of transplantation or transplants of longer duration still on immunosuppressive drugs or with graft-versus-host disease
    * Congenital immunodeficiency
    * HIV/AIDS with CD4 lymphocyte count \<200
    * Neutropenia or expected post-chemotherapy neutropenia within 14 days from the time of screening, defined as absolute neutrophil count \< 500 cells/μL
11. Women who are known to be pregnant or breast-feeding
12. Treatment is not with intent to cure the infection (i.e. palliative care)
13. Unable to collect patient's follow-up data for at least 30 days post-randomisation for any reason
14. Treating doctor deems enrolment into the trial is not in the best interest of the patient
15. Previous enrolment in this trial

Where this trial is running

Singapore, Singapore

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Gram-negative Bacteraemiauncomplicated bacteraemiagram-negative bacteriaearly oral switchantibioticsfluoroquinolonesciprofloxacintrimethoprim-sulfamethoxazole
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.