GADSA: gamified Antimicrobial Stewardship (AMS) decision support app for prescribing behaviour change Antimicrobial resistance is a global problem.  Implementing appropriate antimicrobial prescribing policies and stewardship in clinical and community healthcare settings is one of the powerful ways to reduce antibiotics overuse.  This is of great importance in Nigeria and other Low and Middle Income countries (LMIC) where clinical practice is less regulated. In these countries, due to resource constraints, a widespread over the counter availability of antibiotics and counterfeits create a very challenging environment for implementing antimicrobial stewardship. The Infection Control Africa Network (ICAN), with 28 African member states, has launched the Antimicrobial Stewardship Education Initiative in July 2016 to tackle this issue across the continent. The aim of this interdisciplinary project is to investigate the use of gamified apps on mobile phones and tablets for changing prescription rates through improving compliance with prudent antimicrobial prescription policies, supporting professionals in prescription decision making around three key conditions (urinary tract infections, single dose surgical prophylaxis and upper respiratory track infections). Based on previous study with ICAN and the international Infection Control Resource (iNRIC, www.nric,org,uk) delivering policies and guidance to infection professionals at the point of care, it was identified that African experts preferred accessing policies in a graphical gamified format over their  mobile devices compared to text-based guidelines.  The app will be co-authored and developed jointly with healthcare professionals from two settings (national teaching hospital in Lagos and a community hospital) and evaluated to assess usability and   prescribing behaviour change over a period of 3 months. The cutting edge game-based training technology will enable a customisation support to localize the gamified app to new settings by healthcare professionals themselves. This pilot will demonstrate a new innovation approach with a potential to be cost-effectively scaled up and expanded to cover other AMS policies and settings to support professionals across ICAN member states across the African continent. Our multi-disciplinary team, consisting of computer scientists, epidemiologiest, infection control experts , and a behavioural scientist is ideally placed to develop an app based AMS intervention. We have expertise in app development, AMS guideline translation, and behaviour change, ideally placing us to deliver the proposed programme of work. Moreover, we will co-design our app with users in Nigeria, utilising our existing partnership with ICAN and The College of Medicine of the University of Lagos - affiliated to the national Lagos University Teaching Hospital (LUTH) and regional Obafemi Awolowo University hospital. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.