Common infections and parasites of the GIT Flashcards
Compare the following terms:
- Acute gastritis
- Enteritis
- Gastroenteritis
Acute gastritis: inflammation of the stomach, presents with nausea and vomiting
Enteritis: inflammation of the intestines, presents with diarrhoea
Gastroenteritis inflammation of the stomach to the intestines, presents with nausea, vomiting and diarrhoea
Is gastroenteritis more commonly bacterial or viral?
Viral
How do we prevent spread, in a hospital setting, for a patient with gastroenteritis?
It is essential to isolate the patient
List 3 viral causes of gastroenteritis
- Rotavirus
- Norovirus
- Adenovirus
What is the most common causative organism of food poisoning in the UK?
Campylobacter jejuni (bacteria)
Typical presentation of a of Norovirus infection?
Projectile vomiting and non-bloody diarrhoea around 12-24 hours after consuming seafood
Describe the shape of Campylobacter jejuni
Gram-negative rods with characteristic ‘seagull’ shape
Typical presentation of a Campylobacter jejuni infection
Abdo pain and bloody diarrhoea around 16-48 hours after consuming chicken
Vomiting is rare
Characteristic presentation of Campylobacter jejuni?
- Abdominal pain
- Can cause bloody diarrhoea
- Vomiting is rare
How does Campylobacter jejuni cause gastroenteritis?
Releases enterotoxin in the gut and also invades the mucosa
Complications of Campylobacter Jujuni infection?
Guillain-Barre syndrome
Typical presentation of a Salmonella enteritidis/typhimurium infection?
Watery diarrhoea (+/-mucus or blood), abdominal pain and vomiting around 16-48 hours after consuming eggs and foods contaminated on kitchen preparation surfaces
How does salmonella cause gastroenteritis?
Bacteria multiplies locally in the small and large intestines, invades mucosa and causes inflammation
Typical presentation of a Bacillus cereus infection?
Profuse vomiting around 30mins to 6 hours after eating contaminated rice
How does Bacillus cereus cause gastroenteritis?
Produces 2 toxins
- an emetic pre-formed enterotoxin that is absorbed into the blood-stream from the stomach
- a diarrhoea-causing enterotoxin that acts on receptors in the small intestine and large bowel
Typical presentation of Staphylococcus aureus food infection
Perfuse vomiting, diarrhoea, abdominal cramps and fever. Begin around 1-6 hours after consumption of contaminated milk products and foods contaminated through contact with food workers carrying the bacteria
How does Staphylococcus aureus cause gastroenteritis?
Produces a heat-stable enterotoxin
Typical presentation of E.coli food infection
Watery stools, abdominal cramps and nausea which is common amongst travellers and presents around 16-48 hours after contact with infected faeces, unwashed salads or water
Which strain of E.Coli is most concerning and why?
E. coli 0157, produces the Shiga toxin and causes abdominal cramps, bloody diarrhoea and vomiting
The Shiga toxin destroys blood cells and leads to haemolytic uraemic syndrome(HUS)
What is Haemolytic Uraemic Syndrome (HUS)?
A thrombotic microangiopathy characterized by hemolytic anaemia, thrombocytopaenia and acute renal failure (with normal clotting profile)
Usually affects the very young or old, and is
Typical presentation of Shigella?
Bloody diarrhoea, abdominal cramps and fever around 1-2 days following contact with drinking water, swimming pools and food contaminated by faeces
How does Shigella cause gastroenteritis?
Can produce the Shiga toxin and cause haemolytic uraemic syndrome
Typical presentation of Giardiasis (parasite - Giardia lamblia)
Explosive, watery, non-bloody diarrhoea with an incubation period of 1-3 weeks
Typical history of access to contaminated water, uncooked fruit or vegetables or a lack of hand hygiene (spread via faecal-oral route)
Management of gastroenteritis?
Fluid and electrolyte replacement, food poisoning is usually self-limiting
When do we prescribe antibiotics for gastritis?
- Elderly (or very young)
- Immunocompromised
- Systemically unwell (signs of toxicity)
What antibiotic do we use for Salmonella and shigella?
Ciprofloxacin
What antibiotic do we use for Campylobacter?
A macrolide ie erythromycin
What antibiotic do we use for Cholera?
A tetracycline, to reduce transmission.
Treatment of Giardiasis?
Metronidazole
What bacteria causes Whipple’s disease?
Tropheryma whipplei (+)
List 3 clinical features of Whipples disease
- Malabsorption: diarrhoea, weight loss
- Large-joint arthralgia
- Lymphadenopathy
Gold standard diagnosis for Whipple’s disease?
What would it show?
Jejunal biopsy
Foamy macrophages containing Periodic acid-Schiff (PAS) granules
Treatment of Whipple’s disease?
Long term course of co-trimoxazole
Describe the Clostridium difficile bacteria
Gram (+) rod
What condition does Clostridium difficile cause?
Produces an exotoxin which causes intestinal damage
Leading to a syndrome called pseudomembranous colitis
In what group of people is infection with C.diff most common?
Patients who have recently been on a course of broad spectrum antibiotics
List 4 risk factors for developing a C.diff infection
- Treated with broad-spectrum antibiotics
- > 65 yrs
- underlying conditions (IBD, cancer, CKD)
- weak immune system
- PPIs
- long stay in a healthcare setting
List 2 antibiotics associated with C.diff
- Clindamycin
- Ciprofloxacin
- Cephalosporins
- Penicillins
How does an infection with C.diff present?
- Watery diarrhoea (can be bloody)
- Painful abdominal cramps
- Nausea
- Fever
+ Loss of appetite and weight loss, confusion, signs of dehydration. Ranges from asymptomatic to life threatening
How is C.diff diagnosed?
What characteristic finding is seen?
Clostridium difficile toxin (CDT) in the stool
Characteristic ↑ WCC
First line antibiotics for C.diff?
Vancomycin or Metronidazole
What bacteria causes Cholera?
Vibro cholerae Gram (-)
How does Cholera present?
- profuse ‘rice water’ diarrhoea
- dehydration
- hypoglycaemia
- nausea and vomiting
Management of Cholera?
Aggressive fluid replacement
Antibiotics: Doxycycline or co-trimoxazole
How do we prevent Cholera?
Access to safe water and sanitation
Two oral cholera vaccines are available
