Gastroenteritis Flashcards
Is gastroenteritis only caused by infection?
No, can have many different causes, not just infective
The faecal flora is estimated to have a metabolic capacity equal to what organ?
The liver
What are the 3 main beneficial affects of the commensal flora of the gut?
1) Metabolism
2) Colonisation resistance
3) Antibody induction
What is thought to have a profound effect on the composition of gut flora?
Diet
Which 2 vitamins are secreted by enteric bacteria?
Vitamins K and B12
We are born sterile, what is the difference in the flora of bottle fed babies compared to breast fed babies?
Bottle fed - adult microflora
Breast fed - bifidobacteria
Are the bacteria in the gut mainly anaerobes or aerobes?
Obligate anaerobes (cant survive in presence of oxygen)
What are facultatively anaerobic bacteria?
Can survive in presence or absence of oxygen
What are the 4 most common commensal flora of the gut, what kind of bacteria are they?
1) Bacteroides (anaerobic GNB)
2) Clostridium perfringens (anaerobic GPB)
3) Escherichia coli (Facultative GNB)
4) Enterococcus faecalis (Facultative GPC)
Globally there are roughly how many cases of diarrhoeal disease every year?
1.7 billion
What is the leading cause of malnutrition in children under 5 years old?
Diarrhoea
What are the 8 common bacterial causes of gastroenteritis?
1) Salmonella
2) Shigella
3) E coli
4) Campylobacter
5) Vibrio cholera
6) Clostridium difficile
7) Staph aureus
8) Bacillus cereus
What are the 3 common parasitic causes of gastroenteritis?
1) Entamoeba hist.
2) Giardia lamblia
3) Cryptosporidium
Have outbreaks of foodbourne diseases in England and wales increased or decreased?
Decreased - mainly due to salmonella - more education and better food standards
Have outbreaks of non-foodborne diseases increased or decreased?
Increased - often related to recreational water or animal contact
What are the 5 main presenting complaints for gastroenteritis?
1) Acute onset
2) Vomiting
3) Diarrhoea - frequency, mucous, blood
4) Abdominal pain
5) Systemic effects - fever etc.
What are the 6 complications of gastroenteritis?
1) Dehydration
2) Renal failure
3) HUS - haemolytic urea syndrome
4) Toxic megacolon
5) Guillan barre syndrome
6) Dissemination of salmonella
What are the 3 main investigations in gastroenteritis?
1) Bloods - FBC, U&E, CRP, blood cultures
2) Abdo XR if severe
3) Stool analysis
What 4 tests may be used to analyse a stool in gastroenteritis?
1) Ova, parasites and cysts ‘OCP’
2) Microscopy, culture and sensitivity ‘MC&S’
3) Clostridium difficile toxin ‘CDT’
4) Viral PCR
Name one common viral gastroenteritis?
Norovirus
Norovirus incidence is higher in which season?
Winter
What are the 2 main symptoms of norovirus?
1) Diarrhoea
2) Projectile vomiting
How long does norovirus tend to last, is it dangerous?
24-48 hours, not dangerous
How is norovirus spread?
Via aerosols which come off the vomit of infected people
How is norovirus managed?
Manage dehydration and let illness take its course, stay away from others and diligent hand washing to prevent transmission
What are the 3 main causes of parasitic gastroenteritis?
1) Cryptosporidium
2) Giardia
3) Entamoeba
Cryptosporidium is transmitted how?
Predominantly water borne disease which is spread via contaminated drinking water, swimming pools etc.
Why is cryptosporidium commonly spread via swimming pools?
Oocytes are resistant to chlorine based disinfectants
Is cryptosporidium infection more common in the first or second half of the year, why?
Second half - related to foreign travel and summer holidays
Via which 2 mechanisms can bacteria cause gastroenteritis?
1) Enterotoxin production - toxin produced by bacteria attacks host enterocytes
2) Adherence or invasion of enterocytes by bacteria itself
Other than gastroenteritis what other infection does E coli commonly cause?
UTI
Via what mechanism does E coli cause gastroenteritis?
Enterotoxin production
10-15% of patients with gastroenteritis caused by E coli also develop what complication and why?
Haemolytic urea syndrome
Toxin affects RBCs too
How does E coli infection lead to inflamed and fluid filled bowel?
1) Toxin produced which is internalised by epithelial cells
2) Toxin affects small proteins so that Cl- moves out of the cell followed by Na+
3) High electrolyte content in the lumen also pulls water out in the lumen by osmosis - leading to a fluid filled lumen and dehydration
What are the 4 main types of salmonella?
1) S. typhi
2) S. paratyphi
3) S. enteritidis
4) S. typhimurium
What 3 conditions does salmonella cause?
1) Food poisoning
2) Typhoid
3) Paratyphoid
What is the treatment for infective gastroenteritis?
Supportive management.
Generally avoid Abx as this may increase duration of salmonella carriage
Abx treatment may also worsen E coli HUS (Haemolytic urea syndrome)
What is the difference between tyhpoidal salmonella and non-typhoidal salmonella?
Typhoidal salmonella can disseminate to other cells outside of the GIT and cause typhoidal fever
Why does Abx associated diarrhoea occur?
Due to disruption of the gut microflora which leads to a change in metabolism (carbohydrates/bile acids) and overgrowth of pathogenic organisms
What are the symptoms of Abx associated diarrhoea?
Range from mild diarrhoea to pseudomembranous colitis and can lead to conditions such as toxic megacolon, perforation and shock
What is the most common cause of Abx associated diarrhoea?
C. diff - accounts for 10-25%
Other than C diff what 5 organisms can cause Abx associated diarrhoea commonly?
1) C perfringens
2) S aureus
3) Candida spp
4) Klebsiella spp
5) Salmonella spp
Risk of C diff infection increases massively with increasing…?
Age
What strain of C diff is associated with a 2.5-3.5 fold increased death rate and deaths in younger people?
CD 027
What 2 Abx are high risk for C diff infection?
1) Cephalosporins
2) Clindamycin
What 4 Abx are medium risk for C diff infection?
1) Ampicillin/amoxicillin
2) Co-trimoxazole
3) Macrolides
4) Fluoroquinolones
Which Abx is CD 027 resistant to and is therefore of particular importance?
Fluoroquinolones
What are the 8 CD infection control measures?
1) Early warning system to identify changes in epidemiology
2) Reduce risk of transmission
3) Early isolation/cohorting of patients with diarrhoea
4) Environmental cleaning, chlorine
5) Hand hygiene soap & water
6) Examine/optimise/reduce overall Abx use
7) Limit high risk agents in high risk patients
8) Feedback CDI and Abx data on a regular basis
What 2 Abx are the current therapy for CD infection and what is the new Abx?
Current: Oral metronidazole/ oral vancomycin
New: oral fidaxomicin
Other than Abx what is the other treatment for C diff?
Faecal transplant
