What is a Staphylococcus aureus bloodstream infection?

Staphylococcus aureus (S. aureus) bloodstream infection is one of the most serious bacterial infections worldwide. All patients need to be hospitalised and adults typically will receive a minimum of two weeks intravenous antibiotics.

S. aureus normally lives on your skin or in your nose. It is commonly called ‘golden staph’ as it looks like small golden balls under a microscope. When S. aureus gets into your blood through a sore or a cut in the skin, this can cause a bloodstream infection.S. aureus bloodstream infections can make you very sick and can affect parts of your body like the lungs, heart, bones, and muscles.

There are three types of S. aureus blood stream infection:

• Penicillin-susceptible S. aureus which is also called PSSA
• Methicillin-susceptible S. aureus which is also called MSSA
• Methicillin-resistant S. aureus which is also called MRSA

What is the purpose of this study?

While we have effective antibiotic treatments for S. aureus bloodstream infections, it is not known which of these are the best. There are only a few published studies that compare current available treatments. Fewer than 3,000 participants combined have ever been enrolled in published randomised controlled trials for treatments of S. aureus bloodstream infection. The SNAP study will evaluate a range of antibiotic treatments for S. aureus with the aim of improving outcomes for patients.

There are currently three parts to the study, which we call ‘domains’. To find out more about each of these, please watch the videos below:

•          Antibiotic backbone domain
•          Adjunctive treatment domain
•          Early oral switch domain

Who is doing the study?

The SNAP study is being conducted by researchers across Australia, Canada, New Zealand, Singapore, Israel and the United Kingdom, and has the potential to include sites elsewhere in the world.

The lead sponsor for the study is The Peter Doherty Institute for Infection and Immunity (The Doherty Institute), University of Melbourne.

What happens if I agree to participate in this study?

If you decide to participate in the study, you will be asked to give consent. This means you will be asked to sign a consent form, which you will also be given a copy to keep. You will then be randomly allocated to different treatments in up to three ‘domains’. To learn more about each domain, see our videos here. Each domain has certain eligibility criteria to ensure it is safe for you to participate.

If you agree to take part in SNAP you can withdraw at any time without giving a reason; this will not affect any of the care you receive.

Do I have to take part?

It is ok if you do not want to take part, this decision will not affect any of the care or treatments you will receive while you are in hospital.

If you decide not to participate in the study, you will be given the standard antibiotic treatments that are used in this hospital- which may actually be the same treatments you would have received in the study.

What antibiotics could I be given?

S. aureus bloodstream infections are always treated with antibiotics. The antibiotics used in this study are not experimental drugs. In fact, the antibiotics are already very widely and frequently used in clinical care. 

Most side effects from the antibiotics used are mild, such as diarrhoea, thrush and a rash. Very rarely, more severe side effects might happen, such as liver or kidney impairment, muscle damage or low white cells, but these usually get better when the treatment is stopped. As part of this study the treating doctors will closely monitor you for all of these side effects during your hospital admission and the study medication will be stopped if you experience any severe side effects.

Below is a list of antibiotics which may be used in this study, depending on what country you live in and what domains you take part in:

Treatments that you may be randomly allocated to receive:


Treatments that you may be prescribed by your treating doctor:

Fusidic acid
Trimethoprim plus sulfamethoxazole

Please note: The antibiotics listed in the table above are representative for each drug. If you want to know more about the specific brand that you have been prescribed, please use the following links and search using the antibiotic name:

Australia: Australian Register of Therapeutic Goods
Canada: Canadian Drug and Health Product Register
Israel: TBC
New Zealand: MEDSAFE Consumer Medicine Information
Singapore: TBCUnited Kingdom: MHRA Register of Products

Will it cost me anything to be in this study?

There are no costs associated with participating in this study, nor will you be paid. All medication required as part of the study will be provided to you free of charge.

What do I do if I have a complaint?

If you have any complaints about the conduct of the study or any of the study team you have the right to make a complaint, this will not affect any care or treatment that you are receiving. For contact details to make a complaint please click on the relevant country:

Reviewing Human Research Ethics Committee:
Melbourne Health Complaints contact person
Name: Director Research Governance and Ethics
Positions: Complaints Manager
Telephone: (03) 9342 8530

University of MelbourneName:
Office of Research Ethics and Integrity

SNAP Trial Management Group:
03 8344 2554
Email: snap-trial@unimelb.edu.au

Hospital Research Governance Office
Western Australia
South Australia
Northern Territory
New South Wales
Australian Capital Territory






Who do I call for information after I leave the hospital?

You will be given a participant card with the study team details to keep with you at all times, and you will be able to use the contact details to contact the study team at any time if you have any questions or concerns.

What information will you collect about me?

Almost all of the results collected during your time on this study will be from tests that would have been done even if you were not in the trial.

The hospital staff will record results from your routine tests and observations while you are in hospital (for example blood tests, temperature, symptoms, treatments). You will also be monitored for any side effects. 

As part of the study, we will also samples of bacteria grown from your blood cultures. These will be stored and sent to a central laboratory for analysis. The results from these will help researchers better understand why infections with particular types of S. aureus respond differently to the antibiotic treatments.

We will also ask your permission to link your study information to existing datasets, such as hospital records, medications, emergency department, and registries of births, deaths and marriages, to allow longer follow-up.

As part of the study, we will also collect data for a registry of patients with S. aureus bloodstream infection. The registry will be used to improve current practice and quality of care.

How do you keep my information private?

Any identifiable information that is collected about you in connection with this study will remain confidential and will comply with all relevant country specific privacy legislation. If required, the regulatory authorities and an authorised representative of the trial Sponsor may require access to your personal information to ensure the clinical trial is compliant with the regulatory and safety requirements. The length of storage for identifiers and privacy legislations varies from country to country as indicated below:

Following study close out and locking of the database, data will be stored on the servers of the University of Melbourne. All analyses performed and the final data set will be archived together according to the University standard operating procedures. These records will be kept for a minimum of 15 years after the completion of the trial before being destroyed or erased, as per the National Health and Medical Research Councils guidelines. For further information on Australian clinical trials legislation, regulation and guidelines including the Commonwealth privacy Act (1988) please click here.






What is an adaptive clinical trial?

SNAP is a trial that adapts as we proceed. Once one treatment is found to be clearly better than another treatment, patients will continue to receive the better treatment and the poorer treatment is removed from the trial. With many hospital trial sites around the world, we should be able to recruit patients rapidly and allow us to reach appropriate conclusions as quickly as possible. As data accumulates, trial statisticians will analyse the data in near real-time. An independent data and safety monitoring committee will be reviewing these analyses to ensure patient safety is maintained and that results are acted upon in a timely and appropriate manner.

The advantages over other trial designs is:

  • the trial is continuous

  • as new interventions/treatments become available they can be added into the trial for comparison to current treatments

  • multiple questions can be answered simultaneously

  • answers to questions can be concluded when sufficient data have accrued, not when a specific sample size is met

  • the information collected from patients already participating in the study can be used to help guide the treatment of new patients joining the study

  • Interactions between interventions in different domains can be evaluated

With an adaptive design, existing patients can help guide treatment of new patients. Regular data analysis timepoints are built into the trial and interventions will be changed if during the analyses, an intervention is shown to be either:

  • Much better (continue with this intervention)

  • Currently no difference (continue with interventions until a difference is found)

  • Not as effective (stop this intervention)

  • If a new intervention becomes available include the intervention into the study

If you would like to find out more information about adaptive clinical trials please watch the videos below.

More Information

For further information on our patient support please click below to learn more.

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Our Resources

SNAP Trial Learning Resources

Early Oral Switch Domain

Watch this video to learn more about the SNAP Early Oral Switch Domain.

SNAP Trial Resource

Adjunctive Treatment Domain

Watch this video to learn more about the SNAP Adjunctive Treatment Domain.

SNAP Trial Resource

Antibiotic Backbone Domain

Watch this video to learn more about the SNAP Antibiotic Backbone Domain.

SNAP Trial Resource

Patient Pathway

What does taking part in SNAP mean for participants?

SNAP Trial Resource

Background to Staph aureus bloodstream infections

Learn more about why we’re studying treatments for S. aureus bloodstream infections in the SNAP trial.

SNAP Trial Resource

Background to SNAP

Learn more about why we’re studying treatments for S. aureus bloodstream infections in the SNAP trial.

SNAP Trial Resource