14. Infections Flashcards
What are the key features of the gut immune response to infection?
GALT - peyer’s patches (intestinal mucosa, lymphoid tissue, contain T and B lymphocytes, macrophages and dendritic cells. Sample antigens to prevent inflammation in response to normal bacteria) and mesenteric lymph nodes (lymph from villi and lymph from peyers patches drain into here).
Mucous - barrier.
What is the role of commensal organisms?
Inhabit the large colon and act as competition for ingested infective organisms, stoping overgrowth of the infective organisms.
Describe the clinical approach you would take with a patient presenting with gastroenteritis (history, examination, treatment).
History - include travel and exposure history.
Physical examination - include hydration status, take appropriate samples eg stool and request the right tests.
Treatment - supportive treatment, with or without antimicrobial treatment. Review with test results.
Implement infection prevention and control measures.
What species of salmonella causes gastroenteritis?
Salmonella enteritidis - includes Salmonella Typhi.
How is shigella transmitted?
Faecal-oral. Very low infective dose.
How is norovirus transmitted?
Fecal-oral transmission, very low viral load, with incubation period of 24-48 hours.
What can cause traveller’s diarrhoea?
E. coli, Salmonella, Shigella, Campylobacter and Protozoa (Entamoeba histolytica and Gardia lamblia).
How is cryptosporidium transmitted?
Faecal-oral.
Give 3 infection control measures and infection prevention methods are used to prevent GI infections.
Hand washing.
Isolation.
Environmental cleaning.
48 hours clear of diarrhoea before returning to school, work etc.
How does shigella infection cause gastroenteritis?
Invade and destroy the mucosa of the large intestine, leading to reduced absorption and diarrhoea.
Among what age group is shigella most common?
Young children.
How is salmonella transmitted?
Faecal-oral.
How does salmonella cause gastroenteritis?
Invade epithelial cells, leading to inflammation that kills normal flora, allowing salmonella in intestinal lumen to multiple, causing diarrhoea.
In what group of patients can gastroenteritis be severe, and therefore it can be recommended that they take prophylaxis when travelling, and may need treating with antibiotics if they do contract gastroenteritis?
Immunocompromised patients eg HIV.
How does cryptosporidium lead to gastroenteritis?
Inhabits the epithelial cells of the villi of the lower small intestine.
