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An antibiotic chatbot: Evaluation of a retrieval-augmented generation approach for providing guideline-based antimicrobial advice

David W. Eyre, R. Corrigan, Lauren Hookham, S. Lumley, David Clarke, Katie Jeffery, Louise Dunsmure, Nicola Jones

Journal of Infection, 2026

1 citation

Abstract

BACKGROUND

Large language models (LLMs) have potential to provide clinical infection advice, but variations in prevalent pathogens and antimicrobial resistance requires models to be adapted to local contexts. We evaluated a retrieval-augmented generation (RAG) approach to provide antibiotic and infection advice explicitly constrained to local guidelines.

METHODS

Relevant guideline sections from Oxford University Hospitals were identified combining keyword-matching and a medical embedding model. A locally-deployed LLM (gpt-oss-20b) generated answers using the retrieved context. Performance was assessed using 200 simulated questions with an LLM-as-judge, and 66 human-written questions reviewed by ≥2 infection specialists.

RESULTS

The model attempted to answer 186/200 (93%) simulated clinical advice queries, of which 162 (87%) responses were judged fully-correct, 14 (8%) partially-correct, and 10 (5%) incorrect. Performance was lower in complex scenarios, e.g., when renal impairment was present. For 57 human-written questions covered by guidelines, 46 (81%) single-stage responses were fully-correct and 10 (18%) partially-correct. Of 9 out-of-scope questions, 5 (56%) were correctly identified. A multi-stage pipeline modestly improved performance (84% fully-correct). Median answer generation time was 12 s (single-stage) and 15 s (multi-stage). LLMs without RAG-based local guideline context had lower performance: 21/186 (11%) answers to simulated questions fully correct with the…

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