Session 9: GI Infections Flashcards
Define microbiome.
All the genome within the gut environment
Define microbiota.
The organisms within the gut environment.
Function of the gut microbiota.
Pathogen inhibition
Immune protection (GALT)
Nutrient metabolism (SCFA for the cells of the colon which is produced by the fermentation of dietary fibres)
Drug metabolism
Gut brain axis
What are the most common presenting complaints in GI infections?
Diarrhoea
Vomiting
Pain
What is important to ask the patient about diarrhoea?
Onset
Duration
Frequency
Consistency
What is important to ask the patient about vomiting?
Onset
Frequency
What is important to ask the patient about pain in GI infections?
Site
Radiation
Intermittent/continuous
Give examples of other important questions to ask in GI infections.
Past medical history (Immunodeficient, other GI conditions)
Travel history (Where, when, how long, activities, food and drink, animal contact, travel companions etc…)
Drug history (recent antibiotics, PPis, Laxatives, Immunosuppressants)
Social history
Give examples of GI examination important to do in GI infections.
Volume status
Mucous membranes
Blood pressure
Pulse
JVP
Abdominal examination
Ileus
Peritonitis
What investigations are done in GI infections?
Stool culture
Enzyme immunoassay
PCR
Microscopy
What is gastroenteritis?
Inflammation of the gastrointestinal tract leading to diarrhoea, vomiting and abdominal pain.
Give examples of pathogens that can cause gastroenteritis.
E. coli
Salmonella
Shigella
Campylobacter
Cryptosporidium
Giardia
C. diff
Entamoeba histolytica
Norovirus
Rotavirus
Parasites
How might diarrhoea present in gastroenteritis?
As watery diarrhoea or inflammatory diarrhoea.
How is salmonella generally divided into?
Typhoidal salmonella (Salmonella typhi and Salmonella paratyphi)
Non-typhoidal salmonella (Salmonella enteritidis, Salmonella virchow, etc..)
Where might you find salmonella?
Eggs
Poultry
Turtles
What does Typhoidal salmonella generally cause?
Enteric fever
What does Non-typhoidal salmonella primarily cause?
Gastroenteritis
Incubation period of Non-typhoidal salmonella.
8-72 hours
Transmission route of Non-typhoidal salmonella.
Contaminated food
Faeco-oral route
Animals
General features of Non-typhoidal salmonella.
Watery diarrhoea
Nausea
Vomiting
Abdo cramps
Complications of Non-typhoidal salmonella.
Bacteraemia, endovascular infections, abscesses, osteomyelitis, septhic arthritis.
When might you see Non-typhoidal salmonella causing osteomyelitis and septic arthritis?
In patients with sickle-cell anaemia.
Treatment of Non-typhoidal salmonella.
Usually self-limiting and resolve itself within a day or two.
However in case it is persisting:
Ciprofloxacin, azithromycin, ceftriaxone.
Give common campylobacter pathogens.
Campylobacter jejuni
Campylobacter coli
Where might you find Campylobacter?
In the GI tract of animals, especially poultry.
Incubation period of Campylobacter.
Roughly 3 days
Transmission route of Campylobacter.
Food
Water
Animal contact
General features of Campylobacter.
Abdominal cramping
Watery or bloody diarrhoea
May have fever and malaise
Complications of Campylobacter.
Reactive arthritis
Guillain-Barré syndrome
Treatment of campylobacter.
Usually self-limiting.
In immunocompromised patients, elderly or severe infections:
Macrolides or fluoroquinolones can be given.
Give examples of Shigella.
Shigella dysenteriae 1
Shigella flexneri
What’s important to note about such Shigella?
They can cause dysentery (bloody diarrhoea)
Incubation period of Shigella.
1-7 days
Transmission of Shigella.
Faeco-oral
Food and water.
Person to person can happen due to a low infectious dose.
General features of Shigella.
Fevers
Frequent low volume bloody stools
Tenesmus
Nausea and vomiting is usually absent
Complications of Shigella.
Intestinal:
Systemic:
Intestinal complications are rare but include proctitis, rectal prolapse, toxic megacolon, perforation and obstruction.
Systemic complications such as bacteraemia, seizures, reactive arthritis and haemolytic uraemia syndrome (HUS)
Treatment of Shigella.
Ciprofloxacin
Azithromycin
Ceftriaxone
Give examples of E. coli.
ETEC
EPEC
EIEC
EAEC
STEC
What is E. coli O157?
STEC (Shigella Toxin E. coli)
Transmission of E. coli O157.
Faeco-oral
What age groups are most vulnerable to E. coli O157?
Children under 10 years old and elderly.
Incubation period of E. coli O157.
1-10 days
General features of E. coli O157.
Painful and bloody diarrhoea.
Often NO fever
Complications of E. coli O157.
HUS characterised by nonimmune-mediated haemolytic anaemia, thrombocytopenia and acute kidney injury.
Treatment of E. coli O157.
Fluid replacement and blood pressure agents.
Do not give antibiotics as they can worsen the condition and develop HUS.
Explain what Clostridiodes difficile is.
Anaerobic gram negative bacilli.
One of the most common nosocomial infections.
Risk factors of Clostridiodes difficile.
Age >65
Antibiotic therapy
PPI therapy
Prolonged hospitalisation
Explain how antibiotics can cause Clostridiodes difficile infection.
C. diff can be found in the normal gut flora. However as antibiotics are given the gut flora can be disrupted and C. diff can prosper and start to grow.
Colonisation of the GI tract through faecal oral route. This is exacerbated by antibiotic therapy which disrupts normal gut microbiota.
Give an important virulence factor of Clostridiodes difficile.
Produces spores which are very resistant and remain in the environment for a long time.
Complications of Clostridiodes difficile.
Toxic megacolon
Colitis
Perforation
Treatment of Clostridiodes difficile.
Metronidazole
Oral vancomycin
Fidaxomicin
What is norovirus more commonly called?
Winter vomiting virus/bug
Clinical features of norovirus.
Profuse diarrhoea and vomiting
Incubation of norovirus.
12-48 hours
Transmission of norovirus.
Faeco-oral
Direct contact
Aerosol
It is highly infectious as the infective dose is 10-100 particles (which is very low for a virus)
Treatment of norovirus.
Usually self-limiting and resolves within 1-2 days. Can excrete for longer.
Where does norovirus cause outbreaks?
Hospital wards
Nursing homes
Nurseries
Schools
Cruise ships
Incubation period of rotavirus.
Less than 48 hours.
Transmission of rotavirus.
Faeco-oral
Highly infective
General features of rotavirus.
Diarrhoea
Vomiting
Fever
Usually young children have more severe disease than adults.
Treatment of rotavirus.
Usually self-limiting
Complications of rotavirus.
Seizures
Encephalopathy
Acute encephalitis
They are very rare though
Explain Cryptosporidium.
Intracellular protozoan parasite and associated with sporadic water associated outbreaks.
Affects all age groups but most frequently in children.
Transmission of Cryptosporidium.
Water
Food
Faeco-oral
Person to person
Animals
Incubation period of Cryptosporidium.
7-10 days
Treatment of Cryptosporidium.
Usually self-limiting within 10-14 days.
Nitazoxanide
Clinical features of Cryptosporidium.
Watery diarrhoea
Fever
Nausea
High risk group of Giadria duodenalis.
A protozoan parasite that mainly affect infants, children, immunocompromised, travellers and CF patients.
Transmission of Giardia duodenalis
Food
Water
Faeco-oral
General features of Giardia duodenalis.
Malaise
Steatorrhoea
Abdo cramps
Bloating
Can be asymptomatic
Treatment of Giardia duodenalis
For symptomatic patients
Metronidazole or nitazoxanide
What is Entamoeba histolytica?
Protozoan parasite that can cause amoebic dysentery or infection at extra-intestinal sites like amoebic liver disease.
Risk factors for severe Entamoeba histolytica disease.
Young age
Corticosteroid therapy
Pregnancy
Malignancy
Malnutrition
Alcoholism
Incubation period of Entamoeba histolytica.
2 weeks to years
Transmission of Entamoeba histolytica
Food
Water
Faeco-oral
General features of Entamoeba histolytica.
Diarrhoea (can be bloody)
Abdo pain
Fulminant colitis with necrosis and perforation can occur. This means it can mimic IBD.
Treatment of Entamoeba histolytica.
High dose metronidazole followed by intraluminal agent like paromomycin
Infection and prevention control of gastroenteritis.
Prevent transmission
Contact precautions
Patient isolation and PPE
Hand hygiene with soap water essential in diarrhoeal illness
Terminal cleaning of patient environment.
