Origin,causes and treatments of gastroenteritis using a case study

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Origin,causes and treatments of gastroenteritis using a case study

Lower gastrointestinal infections Case history

‘Bertrand, a 35 year old Frenchman with nausea,abdominal pain and diarrhoea’

Gastroenteritis is a non-specific term used to describe a condition that causes irritation and inflammation of the stomach and intestines in which there is a combination of nausea, vomiting, diarrhoea and abdominal pain.3The gastrointestinal tract contain natural defences which include, gastric acid, bile salts, normal bowel flora, immune responces,motility and protection against toxins by the action of the liver. These influence the nature of local flora and of pathogens that may invade 5. It used to be known as winter vomiting disease1.Micro organisms responsible for gastrointestinal infections vary from one geographic area to another and it depends on the level of sanitation, economic development and hygiene standards. In developing countries it is a major cause of death in children and it is estimated that 4 million children under 5 die from this every year. Usually do to bacteria or parasite contaminating crops and water. In the UK it is estimated that 1 in 5 people will get gastroenteritis and it is usually due to food poisoning. Most cases clear up itself within a week. Severe infections are uncommon in the UK and epidemiology studies have generally noted that rotavirus induced infections peak in the winter and in the summer, bacteria infections are more common.

 

What can cause lower gastrointestinal infections?

Microbes can cause gastrointestinal infections and the common agents are:

Viral: rotavirus (common in children),noravirus (norwalk agent), calciviruses and astroviruses. These are usually self limiting and common in children.

Bacterial: This is a common cause of food poisoning.

Salmonella enterica: is usually associated with drinking un-pasteurised milk.

Shigella: This is the most common cause of dysentery.

Escherichia coli: most common species that cause diarrhoea are: entero-toxigenic and enteropathogenic species. These can either be heat stable or heat labile.

Staphylococcus aureus: This usually causes a mild disease and these species have salt intolerance so are found in salty foods. Staph A is spread mostly through food handling.

Clostridium spp: like perfringens and difficile mostly cause GI in a hospital setting due to the use of antibiotics.

Bacillus cereus: This is most commonly associated with the ‘chinese restaurant syndrome’ caused by fried rice.

Vibrio cholerae: This is spread through contaminated water.

Protozoa: 

Entamoeba histolytica: common cause of amoebic dysentery

Giardia Lamblia: Cysts found in drinking water

Cryptosporidium parvum: through contaminated water.

Parasites: Not a common cause of GI infections but can be caused by some worms.10

 

How do microbes cause lower gastrointestinal infections?

Viruses: can replicate within the villous epithelium of the small bowel and this can cause epithelial cell destruction and villous shortening. This causes a loss of normal absorptive villous cells and their replacement with crypt-like cells that cause the intestine to secrete water and electrolytes.

Bacteria: mucosal adhesion- bacteria must first adhere to the mucosa in the small intestine to prevent them from being swept away if they want to multiply there. Adhesion is caused by hair like antigens termed pili or fimbriae. Toxins that cause secretion-bacteria such as salmonella produce a toxin that alters epithelial cell function. These toxins can reduce the absorption of sodium by the villi and increase the secretion of chloride, this result in the loss of water and electrolytes.Mucosal invasion: Some bacteria can cause bloody diarrhoea by destroying mucosal epithelial cells. Invasion can occur as well and this results in microabscesses and ulcers.

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Protozoa: can adhere to the small bowel epithelium and cause shortening of the villi. Also micro abscesses can occur if the strain is virulent.10

 

What is diarrhoea?

Diarrhoea is usually defined as the passage of three times or more loose or watery stools in a 24hr period. Acute watery diarrhoea- this comes on suddenly and lasts for less than 14 days. Vomiting and a fever may also occur but there is no visible blood in the faeces. Dysentry- This is the presence of visible blood in the faeces. This can then cause anorexia and damage to mucosal cells.The most common cause ...

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