This trial aims to increase the use of antimicrobial stewardship resources when treating patients with respiratory tract infections. This trial is set in Australian general practices (family medicine or primary care).

The main question it aims to answer is which type of implementation activities increase the use of antimicrobial stewardship resources. Researchers will compare doctors who receive face-to-face implementation activities (the Integrated Network group) to those who received virtual or online activities (the Virtual Network group). The primary hypothesis is that there will be a difference in how often interventions are used

Participating doctors will be asked to record how often they use antimicrobial stewardship resources and which interventions they prefer. Participating practices will also provide researchers data on how many patients the doctors see.

Patients with respiratory tract infections who saw a participating doctor will be asked to give feedback on their experience using surveys. A subgroup of doctors, practice staff, and patients will interviewed about their experience in the study.

SUMMARY The OptimasGP study is a two-arm superiority cluster-randomised Hybrid type 3 pragmatic implementation trial to promote the use of antimicrobial stewardship (AMS) interventions by doctors in general practice treating adults with respiratory tract infections.

The implementation strategies used in the trial will be delivered using a Virtual Network (arm 1) and Integrated Network (arm 2) approach. Data collection will collected for five months during winter for the baseline period, followed by implementation activities, and five months in the following winter post-activities.

The primary study outcome is AMS intervention use per 100 consultations. Secondary objectives are based on the RE-AIM framework for reach, efficacy, implementation, adoption, and maintenance of the implementation.

SETTING The study sites for the implementation study comprise 40 general practices across New South Wales, Queensland, Tasmania, and Victoria in Australia.

PARTICIPANTS Participants include 120 general practice (family practice) doctors, 40 practice staff, and patients with respiratory tract infections. Informed consent will be obtained from participating doctors and practice staff in written form by members of the research team. Approximately half of participants will be recruited in 2025, with the remainder recruited in 2026.

Patients will be sent invitations to participate in the study by practice staff via SMS. For patient surveys, completion of surveys will constitute tacit consent. For patients in the case-studies sub-group, informed consent will be obtained in written form by members of the research team.

There are two subgroups. In the first subgroup, three sites from each arm will be elected for the nested case-study (individual semi-structured interviews). For each site, interviewers will construct case studies consisting of 6-8 participants (e.g., 2 doctors, 1-2 practice nurses, 1 practice manager, and 4 ARI patients per case).

In the second subgroup, 3 sites per arm (6-9 doctors) will be provided with FebriDx point of care tests to identify if respiratory tract infections are bacterial or viral in origin. These tests have been approved by the USA FDA (K230917) and by the Australian Therapeutic Goods Administration (ref 346636).

Recruitment and retention will be facilitated by payments to participants.

INTERVENTION RESOURCES Participating doctors will be provided AMS interventions in an online AMS Toolbox (see the latest version at https://redcap.uow.edu.au/redcap/surveys/?s=37HKC3KFMLED7PY7) which they may use when treating eligible patients. The Toolbox will contain AMS interventions resource for shared decision-making between doctors and patients, delayed prescribing, and clinical decision support (including guidance for using FebriDx point of care devices for relevant members of the subgroup).

IMPLEMENTATION ACTIVITIES Both arms will complete ~7 hours of implementation activities. These activities will be provided by MedCast, an established provider of ongoing health professional education in Australia.

Participants in the Virtual arm will receive online self-paced education modules, guided self-audit and reflection regarding antimicrobial stewardship and use of AMS Toolbox components, and reinforcement podcasts.

Participants randomised to the Integrated Network arm will receive education delivered by live interactive online webinar-based sessions, peer-group audit and reflection, and reinforcement online forum participation.

DATA COLLECTION Doctors complete data entry using the AMS Toolbox by selecting if they used an intervention, which intervention was used, and whether an antibiotic was prescribed for immediate use, delayed use, or not prescribed. In addition, the number of patients seen by each doctor will be collected based on a fortnightly record of practice records using surveys.

Demographic data will be collected using online surveys.

Patients will completed patient-reported outcome measures and patient reported experience measures using online surveys. Interviews of the nested-case study sub-group will be qualitative in nature.

All surveys will using REDCap (Research Electronic Data Capture) forms hosted at the University of Wollongong.

RISKS As this study has a low risk of harm or death, and as no interim analyses are planned, the study will not have a Data Safety Monitoring Board. Harms will be recorded through PROMs and direct reports from participating doctors. Harms such as re-consultations and hospitalizations reported to the research team will be discussed with an independent data monitor. This monitor can cease the study at any time if concerns arise. No interim analysis is planned and thus no stopping guidelines are provided.

Study sites

Inclusion Criteria:

1. New South Wales, Queensland, Tasmania, or Victoria
2. at least two GPs per practice consent to be in the study,
3. that at least one member of practice staff consents to be in the study
4. that a staff member from the site will be available to provide 90 minutes per fortnight of administrative support for the study. There are no exclusion criteria in addition to this.

Exclusion Criteria: None

Participating doctors and healthcare workers

Inclusion criteria:

1) Working at a participating practice for at least three days a week. Exclusion criteria : None

Patients completing patient reported outcome measure survey

Inclusion criteria:

1. patients consulted with a participating GP for a RTI,
2. patients re-consulted with a GP or was hospitalized. Exclusion criteria: None

Patient reported experience measures survey

Inclusion criteria:

1) patient consulted with a participating GP for an RTI. Exclusion criteria: None

Patients participating in interviews as part of the nested case studies

Inclusion criteria:

1. consulted with a participating GP for a RTI,
2. completed a patient survey,
3. able to read and speak English Exclusion criteria: None

All IPD that underlie results in a publication will be shared in-deidentified form.

For IPD, data will be available from December 2029.

For supporting information, the protocol paper and statistical analysis plan will be submitted for publication by November 2025. Informed consent form is attached. Analytical code will be provided with the primary outcomes publication.

IPD and supporting data will be available at least until December 2039.

IPD:

Supporting evidence: the protocol will be published in a peer-reviewed journal. Informed consent forms are available on request from the primary investigator or from the study website ().

Analytical code will be provided with the primary outcomes publication