Anyone who has had a urinary tract infection knows how agonising they can be. Some infections go away on their own, but many need antibiotics. Beneath the surface of this very common infection lie many mysteries, unanswered questions, and unnecessary suffering. And it gets to the heart of the challenge of tackling antimicrobial resistance. Madeleine Finlay speaks to Dr Jennifer Rohn, head of the centre for urological biology at University College London, about what we now understand about how UTIs take hold, and the complexity surrounding their treatment. Help support our independent journalism at theguardian.com/sciencepod