Infective Diarrhoea - Revision Flashcards
What is C. diff?
Gram positive rod bacteria
What does C. diff diarrhoea typically follow?
Abx use - abx suppress normal gut flora
What are the 5 most commonly implicated Abx in C. diff diarrhoea?
Broad spectrum:
1) cephalosporins
2) co-amoxiclav
3) clindamycin
4) ciprofloxacin (and other fluoroquinolones)
5) carbapenems
How is C. diff transmitted?
Faeco-oral route
What are 3 risk factors for C. diff ?
1) Abx use
2) PPI use
3) Healthcare settings
How is a diagnosis of C. diff infection made?
1) C. diff antigen –> this only shows exposure to the bacteria, rather than current infection
2) C. diff toxin detection in stool
What c. diff antigen is specifically tested for?
glutamate dehydrogenase
Mx of C. diff infection?
Curent Abx therapy should be stopped.
1st line –> oral vancomycin for 10 days
1st, 2nd and 3rd line therapies for C. diff infection?
1st –> oral vancomycin for 10 days
2nd –> oral fidaxomicin
3rd –> oral vancomycin + IV metronidazole
What is medical management of RECURRENT C. diff infection:
a) within 12 weeks of symptom resolution
b) after 12 weeks of symptom resolution
a) oral fidaxomicin
b) oral vancomycin OR fidamoxicin
Mx of life-threatening C. diff?
Oral vancomycin + IV metronidazole
Consider surgery
What monoclonal Ab is sometimes used in the management of C. diff infection?
Bezlotoxumab –> targets C. difficile toxin B
What may be considered in C. diff infection for patients who’ve had 2 or more previous episodes?
faecal microbiota transplant
Complications of C. diff infection?
1) toxic megacolon
2) pseudomembranous colitis
3) bowel perforation & sepsis
What is pseudomembranous colitis?
Characterised by inflammation in the large intestine, with yellow/white plaques that form pseudomembranes on the inner surface of the bowel wall.
What severe complication can E.coli 0157 cause?
HUS
How does E. coli 0157 cause HUS?
1) E. coli 0157 produces the Shiga toxin
2) Shiga toxin destroys RBCs, leading to HUS
Why should Abx be avoided if E. coli gastroenteritis is considered?
Use of Abx increases risk of HUS
How can HUS present?
Haemolytic anaemia, thrombocytopenia, and acute renal failure post 5–10 days of diarrhoea.
What is the gold standard for diagnosing E. coli?
Stool culture & sensitivity
Main mx of E. coli?
Supportive
Which virus typically causes gastroenteritis with respiratory symptoms?
Adenovirus
Does the presence of blood in acute diarrhoea indicate viral or bacterial cause?
Bacterial - consider campylobacter, E. coli 0157, Shigella
Any child under 3 months old with what temperature should be urgently admitted to hospital?
> 38 degrees
What is the most common causative organism of bacterial gastroenteritis?
Campylobacter
Incubation period of campylobacter?
How long do symptoms last?
2-5 days
3-6 days
1st line Abx in Campylobacter?
Clarithromycin
Classical blood test feature of C. diff infection?
Leukocytosis
Treatment of Shigella?
Normally supportive
What toxin does bacillus cereus produce?
Cerulide (reheating rice kills bacteria but not toxin)
What is the most common cause of infective endocarditis in IVDU?
Staoph. aureus
What is the key carrier of Yersinia enterocolitica?
Pigs (eating raw or undercooked pork can cause infection)
What can Yersinia sometimes be confused with in older children?
Appendicitis:
Older children and adults can present with right-sided abdominal pain due to mesenteric lymphadenitis (inflammation in the intestinal lymph nodes) and fever, which can give the impression of appendicitis.
How is giardiasis transmitted?
Cysts released in faeces of mammals.
The cysts may contaminate food or water. When eaten, they infect a new host (faecal-oral transmission).
Treatment of giardiasis?
Tinidazole or metronidazole
Who should be notified in suspected cases of food poisoning?
The UK Health Security Agency (UKHSA)
Give some post-gastroenteritis complications:
1) Lactose intolerance
2) Reactive arthritis
3) IBS
4) Guillain–Barré syndrome
5) HUS
1st line laxative in constipation?
Bulk forming e.g. ispaghula
Symptoms of amoebiasis?
1) dysentry: profuse, bloody diarrhoea
2) liver abscess: usually a single mass in the right lobe (may be multiple):
- RUQ pain
- fever
- systemic symptoms e.g. malaise
- hepatomegaly
3) colonic abscess
Mx of amoebiasis?
Metronidazole
How does gastroenteritis caused by Staph. aureus present?
Severe vomiting & short incubation period
How can giardiasis affect stool?
Can cause steatorrhoea
Mx of giardiasis?
Metronidazole
What is the purpose of the Yellow Card scheme in the UK?
Encourages healthcare professionals and patients to report any suspected adverse drug reactions, particularly those associated with new (‘black triangle’) drugs.
What are black triangle drugs?
Medicines that are under intensive monitoring because they are either new to the market, or have very limited post-marketing exposure data.
What is the most common cause of travellers’ diarrhoea?
E. coli
What does C. difficile antigen positivity show?
Only shows exposure to the bacteria, rather than current infection.
What is the major dose-limiting side effect of magnesium salts?
Diarrhoea
What is key in determining the severity of C. diff infection?
WCC
NICE recommend a stool sample in what scenarios for diarrhoea?
1) the patient is systemically unwell and needs hospital admission, +/- antibiotics
2) blood or pus in the stool
3) immunocompromised
4) recently received Abx, PPIs or been in hospital
5) recent foreign travel
6) public health indication: diarrhoea in high-risk people (for example food handlers, healthcare workers, elderly residents in care homes), suspected food poisoning
What is the most common cause of type II necrotising fasciitis?
Strep. pyogenes (gram +ve cocci)
What triad is seen in HUS?
1) normocytic anaemia
2) thrombocytopenia
3) AKI
Campylobacter diarrhoea is typically preceded by what?
A prodromal period e.g. fever, malaise and headache.
