GI Infection Flashcards
What is the difference between an endogenous organism and exogenous organism associated with GI infection?
Endogenous:
- due to alteration of organisms within the GI system due to disruption to balance of organisms
- leads to overgrowth of remaining bacteria
Exogenous
-entry of organism into the GI system from environment
What can cause alteration to gut glora?
What organisms is the gut flora made of?
Which organisms are commonly associated with the subsequent infection?
Immunosuppression/medication
Anaerobic and gram negative organisms
Anaerobes i.e. bacteriodes + clostridioides
Gram negative organisms i.e. enterobacteraeciae
Gram positive i.e. enterococcus
Fungi i.e. candida
What are the 3 main types of exogenous organisms responsible for infection?
What are the most common organisms within this types?
Bacteria
- campylobacter
- salmonella, Shigella, E coli
- vibrio
- staph enterotoxin
- clostridium perfringens
Virus
- rotavirus
- norovirus
Parasites
- giardia
- worms
What is diarrhoea?
Inflammation of the intestine leading to them not being able to absorb water from the stool
Therefore leads to water/loose type 5-7 stool which occurs 3(+) time per day
What is gastro-enteritis?
What might someone present with?
Inflammation of stomach and small intestine
Diarrhoae Vomiting Fever Abdominal pains Dehydration i.e. lossing lots of fluid
What is oesophagitis?
What causes it and who is at an increased risk?
What might someone present with?
What would you expect to see on endoscopy and histology?
How is it treated?
Infection and inflammation of the oesophagus
Caused by CMV
-immunosuppressed individuals at increased risk due to weakened immune system enabling reactivation of dormant CMV
I.e. HIV or immunosuppressant drugs or diabetes
Present:
- dysphagia
- odynophagia (painful swallow)
- nausea
- vomiting
Endoscopy= ulcers Histology= inclusion bodies (owl eye appearance which is the location of viral replication)
Tx:
-reduce immunosuppression
+/- ganciclovir (targets CMV)
What is thrush?
What causes it and who is at an increased risk?
What would you expect to see on endoscopy and histology?
How is it treated?
Thrush candidiasis is an overgrowth og candida albicans fungus
Causes:
- steroids/immunosuppression meaning immune system unable to control fungal overgrowth
- antibiotic alteration of flora
White plaques in oral cavity + oesophagus
Tx:
-antifungals= fluconazole
What are the charactertistic features of helicobacter pylori?
What can this bacteria cause?
What tests are used to identify a H pylori infection?
What can untreated H pylori lead to?
How is it treated?
Gram negative rod bacteria
- helical shape penetrates mucosa to avoid acid
- flagella used to motility
- converts urea to ammonia and bicarb using urease enzyme to neutralised stomach acid
Associated with stomach + duodenum ulcers
Urea breath test
-labelled carbon enters stomach in carbonate form where H pylori will convert to CO2 i.e. labelled C can be detected in CO2
Rapid urease test (CLO)
- sample taken on endoscopy and placed on CLO
- change of colour from yellow -> pink == POSITIVE
Untreated:
- stomach cancer
- gastric MALT lymphoma
Treatment= TRIPLE THERAPY for 1 week
- PPI
- clarithromycin
- amoxicillin or metronidazole
What are the key points in a diarrhoea history?
Nature of stool:
-bloody or watery?
Timeline
-when did it start and how long/often since then
Food
Travel
Acute or chronic
How does diarrhoae associate with small bowel differ from that associated with large bowel?
Small bowel
- watery diarrhoae
- caused by enterotoxin i.e. toxins produced by bacteria
Large bowel
- bloody diarrhoae (dysentery)
- caused by direct damage to musosa
What are common infectious causes of watery diarrhoae?
Enterotoxin produced by:
- staph aureus
- clostridium perfringens
- clostridium difficile
- bacillus cereus
- vibrio cholera
What are the common infectious causes of dysentery?
Salmonella
Shigella
Campylobacter
E coli
I.e. gram negative bacilli
Where does staph aureus bacteria live?
How can someone become infected and get diarrhoea?
How might someone present if they had diarrhoea associated with staph aureus infection?
Lives on skin and can be transfered to food
- bacteria multiple on good and produce enterotoxins
- bacteria are killed when food cooked but the enterotoxins survive
Rapid onset of symptoms i.e. 1-6hrs Resolves within day Vomiting Fever Abdo pain
How might someone become infected with clostridium perfringens?
How does the toxin production differ from staph aureus infection and how does this influence the presentation?
What symptoms might someone present with?
Gram positive bacilli which forms spores in food i.e. associated with bulk cooking or when food being left out for long time at inadequate temperatures
Toxins only produced once ingested
- leads to symptoms presenting slightly later i.e. 18-24hrs after (resolves in 1 day)
- no vomiting as toxin only produced once in GIT
Explosive diarrhoea
Cramping
Abdo pain
Ab
Why does a C diff infection occur?
What will someone typically present with?
What complications can occur?
Why does a patient with C diff need to be isolated?
How is C diff treated?
Alteration of colon gut flora leading to overgrowth of C diff
- broad spectrum antibiotics
- PPI= due to changing acidity of stomach
Foul smelling diarrhoea
Fever
Dehydration
Shock= due to toxins produced
Complications occur due to the toxins produced:
- pseudomembranous colitis= yellow plaques
- toxic megacolon= haustra lost on abdo XR
- bowel perforation
C diff spore forming bacteria can survive extreme conditions so need to wait for infectious period to pass to limit the spread
TX: Abx -MILD= metronidazole (IV or oral) -MODERATE-SEVERE= vancomycin (oral or rectal as IV doesn’t reach the gut) -RECURRENT= fidaxomycin Faecal transplant (last resort)
