16 - GI Infections Flashcards
What is the function of the gut microbiota?
- Pathogen inhibition
- Immune protection
- Nutrient metabolism
- Drug metabolism
- Gut brain axis
What is the clinical approach to dealing with a GI infection?
- History (incl travel and exposure history)
- Physical examination (incl hydration status)
- Investigation (samples, tests)
- Supportive treatment (±antimicrobial treatment)
- Infection prevention & control measures
What are some drugs that can cause diarrheoa?
- Laxatives
- PPIs
- Recent antibiotics
- Immunosuppressants
What are some investigations you can do into a GI infection?
- Stool culture
- Enzyme immunoassay
- PCR
- Microscopy (parasites and ova)
Need to tell lab if travel history as this will change their investigations
What is the difference between watery and inflammatory diarrheoa, and what are some examples of organisms which cause each type?
Inflammatory is a smaller amount than watery and it is bloody because there is damage to the mucosa
How does salmonella transmit, what are the symptoms, complications and treatment?
- Non typhoidal causes gastroenteritis (e.g S.enteritidis)
- Invades the small intestine through food, faeco-oral
- Non-bloody diarroea, nausea, vomiting, abdominal cramps
- Usually self limiting 2-3 days
- Complications like abscesses, osteomyelitis, bacteraemia then give antibiotics like ciprofloxacin
How does campylobacter infection transmit, what are the symptoms, complications and treatment?
- Campylobacter jejuni or coli (gram -ve)
- Faeco-oral route in meat products or water, animal contact
- 1-7 days to colonise and then lasts days to weeks but not self limiting
- Abdominal cramping, blood diarrheoa, fever
- Supportive or give macrolides or fluroquinolones if pregnant or immunosuppressed
- Can lead to GBS and reactive arthritis
How does shigella transmit, what are the symptoms, complications and treatment?
- Shigellosis (bacterial dysentry - gram negative)
- Spread person to person, usually contaminated stools
- Small infections dose, 10-100 organisms
- Invades the colon and destroys the mucosa so bloody diarrheoa with mucus and abdominal cramping as mucosal abscess from killing epithelial cells. Fever and tenesmus.
- Shiga toxin is exotoxin
- Usually self limiting
What are some complications of shigella and how would you treat the infection then?
- Rectal prolapse, toxic megacolon, perforation, obstruction
- Seizures, HUS, reactive arthritis
- Give ciprofloxacin or azithromycin
Healthcare and childcare workers need to be cleared before they go back to work as highly contagious
What is the virulence factors of ETEC (enterotoxigenic)?
- Cause of traveller’s diarrhoea
- Transmitted through food and water contaminated by human waste or person to person
- Pili bind to intestinal mucosa and colonise it
- Enterotoxins cause oversecretion of Cl and stop Na absorption so water diarrheoa
What are the symptoms and complications of STEC?
- 1-10 days incubation
- Painful bloody diarrheoa that can lead to HUS
- Made worse by giving antibiotics
What are the virulence factors of C.Diff?
- Anaerobic gram positive
- Normal gut flora but antibiotics can reduce other bacteria and allow this to proliferate
- Toxin A (enterotoxin) stimulates excess fluid secretion
- Toxin B is cytotoxic
- Spores can be produced so disease can occur after antibiotics have been stopped
What symptoms can C.Diff cause and how do you treat it?
- Range from simple diarrheoa to pseudomembranous colitis
- Treated by metronidazole or oral vancomycin
- Wash hands after seeing isolate patient as alcohol hand gel doesn’t kill the bacteria
What are some risk factors for contracting C.Diff?
- Over 65
- PPI therapy
- Antibiotic therapy
- Prolonged hospitalisation
How is norovirus transmitted and what does it present with?
- Faeco-oral route in food or water or contact with infected individuals/surfaces
- Nausea, vomiting and diarrhoea that usually lasts 48 hours and is self limiting
- Highly infectious and can cause outbreaks in schools and hospitals
What are the virulence factors of rotavirus and who does this virus mainly affect?
- Gastroenteritis causing mild to severe non-bloody diarrheoa usually in under 2s
- Faeco-oral route
- Self limiting
- Binds to SI epithelia after surviving acidic environment of stomach. The villi are affected and the surface area for absorption is reduced
- Amount of digestive enzymes reduced so hyperosmotic gut lumen
What is cryptosporidium, how is it transmitted and what does it cause?
- Intracellular parasite that can reside in the ileum
- Spread usually due to animal faces in water supply
- Can cause mild diarrheoa but if immunocompromised, e.g AIDs, can be severe and chronic
- Self limiting 10-14 days
- Treat with nitazoxanide
How does giardia transmit, what are the symptoms, complications and treatment?
- Giardia duodenalis parasite linked to water and travel.
- Spread via water, food, faeco-oral
- Symptoms: malaise, steatorrheoa, abdominal cramps, bloating, can be asymptomatic
- Attaches to walls of duodenum so mild to severe diarrhoea
- Stool sample often negative as high in GI tract
- Metronidazole or nitazoxanide
How do entamoeba histolytica infections present?
- Usually asymptomatic so individual can pass on infection by faecal contamination of water supplies
- If symptoms they will have diarrheoa, abdominal pain, IBS symptoms
