Bacterial and Viral Infections of the Gastrointestinal Tract Flashcards
Intoxication
ingestion of food containing biological active toxins which cause disease
infection
ingestion of live microbes:
- can multiply readily on food prior to consumption
- use food as a vector
then produce toxins within the body
what are the modes of transmission - 5
- faecal-oral
- food
- fluids
- fingers
- person-person
how are diagnosis made for the aetiology (the cause)
patients history and examination: - dysentery - vomiting - abdo pain - travel - food history - speed of onset these all tell you very vital things
enrichment media
promote preferential growth of pathogen
differential media
differentiate micro-organisms by growing in presence of specific nutrients combined with an indicator that changes colour
MacConkey agar
differentiates between lactose fermenting colonies (these turn pink) and non-lactose fermenting colonies (these appear yellow)
why would antibiotics actually worsen a disease
- Prolonging duration
- Promoting toxin release
- Increasing antibiotic resistance
oral rehydration therapy
these mixtures include electrolytes and glucose as these increase the reabsorption of fluids into the intestinal wall - as Na+ and Glucose use the SGLT1 transporter this promotes water transport by osmosis into the cells
alternatives for rehydration therapy if you dont have access to medical fluids
fruit juices, coconut water and other indigenous solutions are alternatives
personal control measures
- hand hygiene
- cook foods properly
- avoid cross contamination
- “wash it, peel it, cook it or forget it”
control public health measures
- pasteurisation of milk and dairy products
- proper sewage disposal
- provision of safe, clean drinking water
- vaccination
what are the three main types of viruses which effect the gI tract
norovirus
rotavirus
adenovirus
s.typhi and paratyphi salmonella
enteric fevers:typhoid and paratyphoid
have only human reservoirs and can cause typhoid fever
they secrete s.typhi in faeces for several weeks after recovery
malaise headache constipation fever bradycardia rose spot rash cough
pathogenesis of salmonella
- Ingestion of a large number of bacteria
- Absorption into the terminal ileum
- Bacteria multiplies in peyers patches (lymphoid of follicles)
- Inflammatory response mediates release of prostaglandins
- Stimulation of cyclic AMP
- Release of fluid and electrolytes causing watery diarrhoea
