Gram-negative gastrointestinal disease

Abstract This chapter reviews the microbiology, clinical features, diagnosis, and management of Helicobacter pylori and Campylobacter infections. It covers the epidemiology, transmission routes, and pathogenic mechanisms of both organisms, including the role of urease in H. pylori survival and adhesins in Campylobacter colonization. Clinical presentations range from asymptomatic carriage to gastritis, peptic ulcer disease, gastroenteritis, and systemic complications such as Guillain–Barré syndrome. Diagnostic techniques, including urea breath testing, biopsy, and stool culture, are outlined. Management strategies include combination antibiotic therapy with a proton pump inhibitor for H. pylori, supportive care for Campylobacter, and targeted antibiotics in severe or prolonged illness. All of the information maps to the RCEM Basic Sciences syllabus, making it relevant to Emergency Medicine practice and the examination.