Infection and Inflammation of the Gut Flashcards
What is Giradiasis?
Chronic, waterborne Protozoal infection
What are the symptoms of a Giardiasis infection?
Diarrhoea
Malabsorption
Weight loss
Asymptomatic
What is Giardiasis treated with?
Metronidazole
What subset of people are most likely to get a CMV infection?
Immunosuppressed patients
- organ transplant from seropositive donor associated with immunosuppressive therapy
- bone marrow transplant
- AIDS patients
What are the clinical signs of CMV infection?
Severe pain Loss of weight Weakness Remitting fever GI lesions - erosive-ulcerous - ulceronecrotic
What is Whipple’s disease?
Infection of the GI tract by Tropheryma whipplei
Patients have lack of immunity to the organism
What are the clinical signs of Whipple’s disease?
Weight loss
Arthralgia
Diarrhoea
Abdominal pain
How is Whipple’s disease diagnosed?
On biopsy of the duodenum
- shows PAS positive macrophages
What is tropical sprue?
Post-infectious sprue
Malabsorption disease
Affects people living in or visiting the tropics
What is the cause of tropical sprue?
E.Coli
Haemophilus
What is the pathophysiology of Tropical sprue?
Malabsorption disease that presents within weeks of an enteric infection
- flattening of villi
- inflammation of the lining of the small intestine
What is the treatment for tropical sprue?
Long course of tetracycline
Name the 6 intestinal diseases that can arise in an Entamoeba Histolytica infection.
Asymptomatic intralumincal ameobiasis-pass cysts
Dysentery
Acute necrotising colitis with perforation
Toxic megacolon
Ameboma
Perianal ulceration with fistula formation
Describe asymptomatic intraluminal ameobiasis-pass cysts.
Can involve any part of the bowel
Small foci of necrosis that progress to ulcers
- flask-shaped ulcer with narrow neck and broad base
Infection is initiated by ingestion of faecally contaminated food or water
Can spread to the liver, thorax and brain
Where can an amoeba infection spread?
Metastasis can occur overwhelmingly to the lover
- can spread from there to the thorax or even the brain
Rectovesicular fistula and fistulous involvement of the skin have been reported
What is pseudomembranous colitis and how is it diagnosed?
Swelling/inflammation of the large intestine due to overgrowth of C.Diff bacteria.
Loss of cypts
Diagnosed by C.Diff toxin found in the stool
What is the pathophysiology of pseudomembranous colitis?
Often prior treatment with antibiotics (e.g. clindamycin) causes elimination of many gut commonesuals and overgrowth of toxin, producing C.Diff
How is a mycobacterium tuberculosis infection of the colon diagnosed?
Biopsies show granulomatous inflammation with confluent granulomas, usually with central caseous necrosis
- contains multi-nucleate giant cells
Ziehl-Neelsen stain, culture and PCR can also identify the bacteria
What is the treatment of a mycobacterium tuberculosis infection?
Multiple antibiotics - Isoniazid. - Rifampin - Ethambutol - Pyrazinamide More aggressive treatment for multidrug resistant TB Surgery if the granuloma is perforated or obstructing - fish mouth stricture
Which parts of the colon is most commonly involved in colonic TB infections?
Cecum in conjunction with the ileum
- abundant lymphoid tissue
- often occurs in the absence of active pulmonary disease
How does the mycobacterium tuberculosis infection spread to the colon?
Swallowed bacteria
Haematogenous spread
Direct extension from infected lymph nodes or uterine tubes
What are the common clinical features of a colonic TB infection?
Weight loss Anorexia Fever Abdominal pain Diarrhoea Palpable mass
Name some possible endoscopic findings in colonic TB.
Strictures
Ulcers
Mucosal hypertrophy
What is a schistosomiasis infection of the colon?
A fluke that causes colitis or bowel obstruction
Associated with underdeveloped countries and living near a dam reservoir
How can a schistosomiasis infection of the colon be diagnosed?
Can be seen down the microscope on a biopsy sample
What are the criteria for performing a duodenal biopsy in coeliac disease?
Symptomatic patient with serological markers
Symptomatic, seronegative patients who are DQ2/8+ve
Asymptomatic others if they at risk of being seropositive
- T1DM
- 1st degree relative
- Down’s syndrome
While on a gluten-containing diet
Four biopsies taken irrespective of endoscopic appearances
What are the features that support a diagnosis of coeliac disease?
Coeliac-associated antibodies
HLA-DQ2 and/ or DQ8
Response to gluten exclusion
Histology
What is the histopathology of coeliac disease?
Villous atrophy
Crypt hyperplasia
Increased number of intra-epithelial lymphocytes
Increased number of plasma cells in the lamina propria
(more than 25 to 100 lymphocytes)
Who should you offer serological testing for coeliac disease to?
Persistent unexplained abdominal or GI symptoms
Faltering growth
Prolonged fatigue
Unexplained weight loss
Severe or persistent mouth ulcers
Unexplained iron, vitamin B12 or folate deficiency
T1DM at diagnosis
Autoimmune thyroid disease
IBS (in sdults)
First degree relatives with coealiac disease
Name come clinicals signs of malabsorption.
IDA Steatorrhoea - bulky, pale, greasy and offensive smell Osteopenia/prosis - increased risk of fracture
Describe the pathology of acute appendicitis.
Acute inflammation in mucosa followed by ulceration and transmural inflammation
What are the complications of acute appendicitis?
Transmural gangrene leading to perforation
Generalised peritonitis
Right iliac fossa pain
Chronic ‘grumbling appendix’
What is diverticular disease?
Mucosal out-pouchings through the muscle coat of the colon
Which part of the colon does diverticular disease principally affect?
Sigmoid
Describe the pathophysiology of diverticular disease of the colon.
Low roughage diet causes constipation and high sigmoid luminal pressure
- herniation of mucosa through weakness in the muscle coat of the sigmoid
What are the complications associated with diverticulitis?
May perforate - abscess or faecal peritonitis May fistulate into the bladder or bowel May bleed May obstruct the bowel
What history would you expect from a person with microscopic colitis?
Middle aged person Profuse watery diarrhoea - 10 motions per day Colonoscopy normal Histology abnormal
Name and describe the two types of microscopic colitis.
Collagenous colitis
- inflammatory bowel disease
- collagen deposition in tche lamina propria
Lymphocytic colitis
- more inflammation
- accumulation of lymphocytes in the epithelium and lamina propria
What can cause microscopic colitis?
Secondary to drug treatment
- NSAIDs
- antidepressants
- PPIs
- statins
What is the treatment for microscopic colitis?
Eliminate causative drug
Treat with 5-aminosalicylic acid or Budesonide
What are the acute and chronic symptoms of ischaemic gut?
Acute - sudden onset abdominal pain - blood in PR Chronic - abdominal angina: pain associated with eating - weight loss
Name some possible causes of ischaemic gut.
Mesenteric artery or vein thrombosis Mesenteric artery embolus Hypotension (watershed infarction) Strangulation hernia Volvulus - twisting gut
Describe the pathology of ischaemic gut.
Mucosal and transmural infarction
Coagulative necrosis
Gangrene
May require surgical resection
What would you expect to see on endoscopy in an ischaemic bowel?
Petechial haemorrhages Oedematous and fragile mucosa Segmental erythema Scattered erosion Longitudinal ulcerations Sharply defined segment of involvement
Name some complications of ischaemic gut?
Intestinal gangrene in 1-4 days Bacterial superinfection Enterotoxin formation (pseudomembranes) Stricture Peforation can be fatal Tachycardia Peritonism signs
