infectious diarrhoea Flashcards
Define diarrhoea
Fluidity and frequency of stool
Define gastro-enteritis
Three or more loose stools/day
inflammation of the small intestine
Define dysentry
Inflammation of the large bowel
Bloody stools often containing mucous
What stool chart is used to describe consistency and appearance of stool
Bristol stool chart
What can cause gastro-enteritis
Contamination of foodstuffs - e.g campylobacter
Poor storage of food
Travel related infection
Person to person spread e.g norovirus
What is the most common gastro-enteritis causing bacteria
Campylobacter
Which foodborne bacteria causes the most admissions in hospital
salmonella
What are the defences against enteric infections
Stomach acidity
Normal gut flora
immunity
What can cause the stomach acidity to reduce
Antacids and PPIs
What is the common opportunistic bacteria in the gut when the normal flora is dirupted
C difficile
What are non inflammatory diarrhoeal pathogen examples
Cholera
Enterotoxigenic E.coli
What are the symptoms of non-inflammatory diarrhoeal ilness
Frequent watery stools with little abdo pain
Usually no pain and fever due to no inflammation
What is usually the management of non inflammatory diarrhoeal illness
Rehydration therapy
How does cholera cause diarrhoea
It releases the cholera toxin which stimulates cAMP which causes increase loss of chlorine from cells - the water then follows the chlorine which leads to it being excreted
What are common pathogens which cause inflammatory diarrhoeal illness
Salmonella and campylobacter
What are the symptoms of inflammatory diarrhoeal illness
Pain and pyrexia
What is the treatment of inflammatory diarrhoeal illness
Antibiotics can be helpful but are not necessary if the patient has a healthy immune system
Rehydration therapy is the most important treatment
How long does infective gastro-enteritis usually last
2 weeks
What will be seen on examination and in investigations for bacteria causing diarrhoea
Risk of food poisoning
Assess hydration - patients usually dehydrated therefore they will have a postural drop in blood pressure when they stand up, low skin turgor and tachycardia
On bloods, may see signs of inflammation e.g CRP and raised WCC
What investigations are done when for patients with suspected bacterial causing gastro-enteritis
Stool culture
blood culture
renal function - increased fluid loss can cause harm to kidneys
blood count - raised WCC
Xray/ CT
What is the differential diagnosis for bacterial causing gastro-enteritis
Inflammatory bowel disease
Spurious diarrhoea
carcinoma
Sepsis outside the gut
What is spurious diarrhoea
Patient is so constipated that they can only excrete fluid which escapes between the gaps in the constipated bowel
What is the treatment for gastro-enteritis
Rehydration :
Oral rehydration with salt/sugar solution
IV saline
How long is the incubation period of campylobacter and how long does it take to become cleared
7 days incubation period
Cleared within 6 weeks
What is a complication of campylobacter
Post-infection sequelae - developing autoimmune condition after having an immune response to an infection
What are the stool investigations done gastro-enteritis
Stool culture - can identify the bacteria and see how it reacts to different forms of bacteria
PCR - viral suspicion
Immunoassays - if bacterial invasion suspected
What is used in culture to specifically look for capmpylobacter
Campylobacter specific agar
How is salmonella transmitted
Eating/drinking contaminated food and water
Touching infected animals
The bacteria lives in the intestines
What is the incubation time for salmonella
upto 48 hours
What are the symptoms of salmonella gastroenteritis
Inflammatory diarrhoea - therefore pyrexia and abdominal pain with diarrhoea
Who is most at risk of salmonella gastroenteritis
Elderly, young, immunocompromised , those taking antacids which reduce stomach acid
What does E.coliO157 cause
Characterised by frequent bloody stool
Haemolytic uraemic syndrome - haemolytic anaemia, thrombocytopenia and renal failure
How is E.coli O157 spread
Contaminated meat or person to perosn
What happens in haemolytic-uraemic syndrome
The shigella toxin stimulates platelet aggregation which blocks vessels - the red blood cells try squeeze through which causes haemolysis where they are broken down
The uraemia is caused by renal failure when the renal arteries are affected
How does staph aureus cause gastroenteritis
release of a toxin
What is found in re-fried rice
Bacillus cereus - allows spores of bacillus to open up when the rice is reheated which releases the toxins to the gut
What is found is clostridium perfringens found in
Undercooked/ left out meat
When are antibiotic indicated in gastroenteritis
Immunocompromised
sepsis
Chronic illness such as cancer
What are the 4 antibiotics that can disrupt the gut flora leading to C difficile invasion
4 C antibiotics
Cephalosporin, Co-amoxiclav, ciprofloxacin and clindamycin
What is the treatment of C difficle
Metronidazole first line
Oral vancomycin
What is given as treatment if there is severe colitis caused by C difficile
Oral vancomycin with IV metronidazole
How are parasites diagnosed
Microscopy
What is giardia duodenalis
Protozoan parasite which is a travellers parasite and is more common in men
describe cryptposporidium
Causes diarrhoea, nausea and vomiting with abdo pain
Transmitted through infected animals and faeces - contaminated water and food
What does entamoeba histolytica cause
Bloody diarrhoea - dysentry
Liver abscess
How is entamoeba histolytica treated
Metranidazole and luminal agent to flush out the invasion
What is rotavirus
Paediatric virus - children version of Norovirus
Has a vaccine for rotavirus
When is norovirus more common
Winter
What is norovirus
Disease which causes diarrhoea and viruses and has common outbreaks in hospital
How is norovirus diagnosed
PCR
