Combined Infection Training ST3 Interview Question Bank

The Medibuddy Combined Infection Training ST3 Question Bank includes over 40 scenarios that closely mirror the real interview, each with a model answer written/edited by high-scoring candidates who sat the Combined Infection Training ST3 interview in 2026.

However, knowing a strong answer isn't the same as delivering it well under pressure, which is why we provide:

Study Groups with candidates across the country
Unlimited Live Mocks with real people
Peer Feedback on your mocks from a wide range of candidates

10 years’ experience preparing doctors for interviews

Users of the Medibuddy Combined Infection Training ST3 Revision Platform have secured some of the most competitive training jobs in recent rounds. Ask around, there's a good chance the trainees in the year above you used us too.

Always up to date

Did you know the interviews change every year? That's why we review and update every Question Bank on the platform twice a year, so you know you're always practising with scenarios based on the latest interview structure.

Network and practise real interview scenarios with other candidates

Question Bank

See every scenario, and how to answer it well

Over 40 scenarios across both interview stations, which tell you exactly how to respond to each question.

Study Groups

Connect with candidates across the country

Most people only ever practise with one or two friends. Study Groups connect you with candidates right across the country sitting the same Combined Infection Training ST3 interview.

Live MocksBeta

Practise interview technique with different candidates

Arrange or get matched on demand with other candidates and run real scenarios out loud under interview conditions. Those who practise with the widest range of people tend to score the highest.

Peer FeedbackBeta

Reviewed by candidates across the platform

Submit your recorded mocks to candidates across the platform and get honest, varied feedback. Reviewing other people's mocks teaches you just as much.

The question bank, and other candidates to practise with, all in one platform.

What candidates say

Scored well, secured their post

A few of the candidates who prepared with us for the Combined Infection Training ST3 interview.

Verified candidateInterviewed 2026

"The clinical scenarios were pitched exactly right. Having a structure ready meant I could work through a complex infection case calmly under pressure."

Secured first-choice deanery

Verified candidateInterviewed 2026

"Practising the presentation and ethics questions out loud with other candidates was the single most useful thing I did before the day."

Ranked highly

Part 1 • See the questions

The Medibuddy 2027 Combined Infection Training ST3 Question Bank

The interview has two stations and four questions and takes around 30 minutes, so you have a limited window to deliver the high-scoring answers you need to do well. That means every point has to land, and knowing how to structure each answer is essential. That's why each of our 40-plus scenarios comes with a model answer, written by candidates who scored highly in the 2026 Combined Infection Training ST3 interview, so you know exactly how to approach every question the interviewers throw your way.

What's inside

What's included in the Combined Infection Training ST3 Question Bank

There's nothing worse than getting to the interview and being handed a scenario you've never seen before. The panel can draw on clinical, presentation, suitability and ethical themes across both stations, so the safest approach is to revise across all of them. We provide scenarios for every part of the interview, including the common ones and the more unusual cases that have come up before, so you don't get caught out.

Clinical Scenarios

Infection and general medical cases where you play the registrar: assess, reason and manage safely, each with a worked answer showing how to structure your response.

Presentation

A three-minute presentation on an interesting recent development or research finding relevant to the infection specialties, followed by discussion. We provide guidance on choosing a topic and structuring it well.

Suitability & Commitment

Your chance to show your motivation for the infection specialties and why you're suited to ST3, with example questions and model answers.

Ethics, Professionalism & Governance

Realistic ethical and legal dilemmas, with structured model answers so you can reason through them clearly on the day.

Reflecting how CIT is really assessed

Communication runs through the whole interview, and your scores form a Raw Interview Score with an appointability threshold. Our model answers are written with that in mind, alongside the clinical, presentation, suitability and ethical themes.

Try it

Try an example Combined Infection Training ST3 question

You are the ST3 on the infectious diseases ward. A 29-year-old man who injects drugs presents with a four-week history of malaise, fevers and increasing breathlessness. He denies chest pain, cough or urinary symptoms.

Observations: temperature 38.2, heart rate 105, blood pressure 112/72, SpO2 96% on air. He looks tired, with track marks on both arms but no abscesses. Cardiovascular examination reveals a systolic murmur. His chest X-ray and urine dip are normal.

How would you approach this?

Question

What is your approach?

Example answer

The most likely diagnosis is infective endocarditis.

Immediate: an ABCDE assessment, checking stability, giving fluids if hypotensive and monitoring for sepsis, with IV access and close observation.
History: the timeline of fever and malaise, night sweats and weight loss, any structural or prosthetic valve disease, prior endocarditis or indwelling lines, and embolic symptoms such as stroke, back pain or abdominal pain.
Examination: the peripheral stigmata of IE, such as splinter haemorrhages, Osler's nodes, Janeway lesions and Roth spots, plus murmurs, signs of heart failure and embolic signs.
Investigations: at least three sets of blood cultures from separate sites before antibiotics, bloods including an HIV screen, echocardiography (TTE first, TOE if high suspicion or a prosthetic valve), and urine for haematuria.

I would withhold empirical antibiotics until cultures are taken, unless he is septic or shocked.

Question

What is in your differential diagnosis?

Example answer

Infective endocarditis is most likely in an injecting drug user with prolonged fever and a murmur.
Other infections: TB, HIV, viral infections, and deep-seated infections such as osteomyelitis, discitis or a liver abscess.
Non-bacterial thrombotic endocarditis.
Non-infective causes: malignancy such as lymphoma or leukaemia, autoimmune disease or vasculitis such as SLE or ANCA-associated vasculitis, and inflammatory disorders such as IBD or sarcoidosis.

Question

What are the modified Duke criteria?

Example answer

Major: positive blood cultures with typical organisms (such as S. aureus, viridans streptococci or enterococcus), and evidence of endocardial involvement (a vegetation, abscess or prosthetic valve dehiscence on echo, or new valvular regurgitation).
Minor: a predisposition (injecting drug use, prosthetic valve, congenital heart disease), fever of 38 or above, vascular phenomena, immunological phenomena, and a positive culture not meeting the major criteria.

Definite IE requires 2 major, or 1 major plus 3 minor, or 5 minor criteria.

Question

What are the common causative organisms?

Example answer

Native valves: Staphylococcus aureus (especially in injecting drug use and acute presentations), viridans group streptococci and enterococcus.
Prosthetic valves: Staphylococcus aureus, coagulase-negative staphylococci and enterococcus.
Rarer: the HACEK organisms, and culture-negative causes such as Coxiella burnetii, Bartonella and Brucella.

Question

What are the long-term management considerations?

Example answer

Antibiotics: a prolonged course of IV antibiotics, typically 4 to 6 weeks guided by cultures, with an earlier oral switch in selected patients (as in the POET study), monitoring renal function and drug levels.
MDT: microbiology, infectious diseases, cardiology and cardiothoracic surgery, with dietetics, physiotherapy and specialist nurses.
Surgery for severe regurgitation with heart failure, a perivalvular abscess (watching the PR interval for heart block), large vegetations with recurrent emboli, persistent bacteraemia, or prosthetic valve endocarditis.
Complications and prevention: monitor for septic emboli, immune complex phenomena and heart block, test for HIV and hepatitis, address harm reduction, and educate him on recurrence risk.

That's one scenario. There are over 40 more.

Actively maintained

How we keep our Question Banks up to date

The Combined Infection Training ST3 interview changes from year to year, and the biggest fear for any candidate is getting to interview day and realising you've revised with a question bank that's totally outdated.

That's why we review and update every Question Bank twice a year, so you know you're revising with scenarios that are likely to come up. We do this in April after the previous year's interviews, and again in the autumn when the new recruitment guidance is published.

For 2027, this process kept the Question Bank aligned with the current two-station structure, including the three-minute presentation, so you always practise with the format the panel is using now.

Updated for 2027 Interviews

Part 2 • Practise them live

The only interview resource where you can practise live with other candidates from across the country

Our Combined Infection Training ST3 Question Bank tells you exactly how to answer real interview scenarios. But how you practise with them will determine how many marks you score. Simply reading answers off a screen won't prepare you for the intense scrutiny you'll face in the interview. And only practising with the same few colleagues or friends limits the amount of feedback you'll get. Medibuddy gives you unique access to Combined Infection Training ST3 candidates across the country, so you can learn from a variety of perspectives and hear a far wider range of feedback than your own circle could ever give you.

Study Groups

When you prepare in isolation, you're relying on your own interpretation of the interview process, which is one of the quickest ways to get found out on the day. Study Groups connect you with other doctors across the country who are also applying to Combined Infection Training ST3, so you can engage and network with people preparing for the same interview as you. Everyone brings different experience from different hospitals and deaneries, meaning you won't ever miss out on the key bits of information that could swing the interview in your favour.

Live MocksBeta

Candidates who don't take part in mocks often struggle to adapt to the pressure of the interview. Your knowledge might be correct, but without convincing delivery the interviewers will score you poorly. The best way to improve your delivery is to take part in as many live mocks as possible, which is why we haven't put a cap on how many you can do. We also know how difficult it can be to organise mocks with other people, so all you have to do is join the waiting room and we'll match you with a different Combined Infection Training ST3 candidate each time. Take turns as both the interviewer and candidate on real Question Bank scenarios, so you can see exactly how other candidates perform in real time, while refining your own interview technique.

Peer FeedbackBeta

Preparing alone means you won't know how you're coming across during the interview. And preparing with the same few candidates means you'll miss opportunities to improve, which is why it's so important to get as many opinions as possible on your performance. With Medibuddy, you can record a mock and submit it for feedback from other candidates on the platform, so you receive a wider range of feedback and refine your answers with each person you practise with. Reviewing other people's mocks is just as valuable, as it shows you how strong candidates handle the same scenarios, which is one of the fastest ways to improve.

The interview