GI - Acute and Chronic Diarrhea + IBS and IBD Flashcards
Ddx infective and non-infective causes of acute diarrhea
Infective: → Gastroenteritis (vast majority) → C. difficile infection → Other GI infections, eg. diverticulitis → Malaria
GI non-infective:
→ IBD
→ CA colon
Metabolic: → DKA → Hypocalcaemia → Uraemia → Thyrotoxicosis → Neuroendocrine diseases
Drugs: antibiotics, NSAIDs, cytotoxic agents, PPI
Toxins: ciguatera fish poisoning, heavy metal poisoning
Acute diarrhea
4 pathological groups of infective causes + examples
- Food poisoning - preformed toxins:
B. cereus
S. aureus
Clostridium perfringens
2. Non-inflammatory, small bowel: V. cholerae Enterotoxigenic E. coli Norovirus Rotavirus (children) Giardia lamblia Cryptosporidium parvum
3. Inflammatory, large bowel: EHEC* Shigella* Campylobacter Non-typhoidal Salmonella Clostridium difficile Entamoeba histolytica*
- Invasive:
Salmonella typhi
Salmonella paratyphi
(Yersinia)
Infective food poisoning
- Bacteriology
- Pathogenesis
- Incubation period
- Presentation
Non-inflammatory acute GE
- Bacteriology
- Pathogenesis
- Incubation period
- Presentation
Inflammatory acute GE
- Bacteriology
- Pathogenesis
- Incubation period
- Presentation
Invasive acute GE
- Bacteriology
- Pathogenesis
- Incubation period
- Presentation
Acute GE in winter months, children predominant
Present with vomiting, diarrhea, prodromal features for few days
Most common pathogens
Viral causes: majority of acute GE, usually mild
□ Norovirus: accounts for >1/3 of outbreaks
→ Esp common in winter months
□ Other viruses: usually causes ds in children
→ Eg. rotavirus, adenovirus, astrovirus
Acute GE presents with severe watery diarrhea within hours of meal
Similar features in people who share meals
Most likely causative pathogens
□ Toxin-mediated: a/w food poisoning
→ S/S: prominent N/V w/ short incubation
→ Eg. B. cereus typically a/w rice
→ Eg. S. aureus typically a/w prepared food
Acute GE, presents with watery, large volume diarrhoea a/w abdominal cramping, bloating and gas
Over 3-5 days
No blood in stool or fever
Most likely causative agents
Non-inflammatory pathogens:
V. cholerae Enterotoxigenic E. coli Norovirus Rotavirus (children) Giardia lamblia Cryptosporidium parvum
Acute GE, presents with frequent, regular, small volume and often painful bowel movements
a/w fever and bloody/mucoid stools
Most likely pathogens
Inflammatory pathogens
EHEC* Shigella* Campylobacter Non-typhoidal Salmonella Clostridium difficile Entamoeba histolytica*
Define likely pathogens associated with following food:
Rice Seafood Raw eggs Uncooked meat, poultry Unpasteurized dairy products Canned food
Rice: Bacillus cereus
Seafood: Norovirus, Vibrio spp, hepatitis A
Raw eggs: Salmonella spp
Uncooked meat, poultry: Salmonella spp, Campylobacter spp, EHEC, C. perfringens
Unpasteurized dairy products: Salmonella spp, Campylobacter spp, EHEC, Yersinia enterocolitica
Canned food: C. botulinum
Outline history taking for acute diarrhea
□ Diarrhoea: syndrome, duration, amount, frequency, presence of blood, mucus or fat
□ Associating symptoms: abdominal pain, fever, N/V, poor appetite
□ Food history: intake, changes in preparation or content, unhygienic food
□ Travel, occupation, contact, cluster
□ Dehydration: frequent profuse watery diarrhoea, vomiting, poor fluid intake, concurrent fever, dry lips, oliguria
□ Other Hx: recent Antibiotics use, immunodeficiency
Clinical definition of diarrhea
Increase daily stool volume, frequency and fluidity
Stool weight > 250g/ 4h
> 2-3 times/ day or liquidity
First-line investigations for acute diarrhea
Indication for investigation
Basic metabolic panel: CBC, L/RFT, electrolytes ± blood culture
Stool examination:
→ Stool culture for bacterial pathogen
→ Stool microscopy for RBC, WBC, ova and cyst (if inflammatory or persistent)
→ Multipathogen panel for bacterial, viral and parasitEic pathogens (if inflammatory)
→ Specific toxin tests: E. coli O157:H7 test, Shiga toxin test, C. difficile toxin testing
Malaria workup: thick/thin blood smear if returning traveler
Indications:
severe illness, inflammatory diarrhea with high fever, persistent for > 1 week, high risk comorbidities and diseases
First-line management of acute diarrhea
Fluid: ORS or IV fluid if shock, unconscious
Antibiotics: ONLY FOR SEVERE or INFLAMMATORY DIARRHEA
Empirical Tx: azithromycin (if inflammatory) or fluoroquinolones
Specific Tx: metronidazole (C. dificile), amoxicillin/cotrimoxazole (Listeria)
Anti-diarrhoeal, eg. loperamide (Imodium), bismuth salicylate for inflammatory diarrhea
Clinical definition of chronic diarrhea
Categorize chronic diarrhea into 3 main pathophysiological groups
Definition: Loose stool > 4 weeks with >3 loose stools/ day
- Inflammatory: Inflammatory bowel diseases, chronic infections, colonic diseases
- Watery: Secretory, Osmotic and Motility problems
- Malabsorption
Inflammatory causes of chronic diarrhea
Inflammatory bowel ds:
Crohn’s disease
Ulcerative colitis
Chronic infections:
C. dificile
M. tuberculosis
Other colonic diseases:
CA colon
Chronic ischaemia
Malabsorptive causes of chronic diarrhea
Causes: small bowel diseases, gut resection, bacterial overgrowth, pancreatic diseases
e. g.Enteropathy: celiac disease, short gut syndrome, Crohn’s disease
e. g. Pancreatic insufficiency: chronic pancreatitis, CA pancreas
Secretory causes of chronic diarrhea
Endocrine tumours: VIPoma, carcinoid syndrome, Zollinger-Ellison syndrome
Bile salt malabsorption e.g. terminal ileum diseases/ resection
Laxative abuse
Osmotic causes of chronic diarrhea
Lactase deficiency
Osmotic laxative
(Malabsorption)
Hyper-motility causes of chronic diarrhea
IBS
Metabolic: hyperthyroidism
Chronic diarrhea presenting with Mucoid, bloody stools with PMN in stools
Most likely causes?
Inflammatory bowel ds
Crohn’s disease
Ulcerative colitis
Chronic infections
C. dificile
M. tuberculosis
Other colonic diseases
CA colon
Chronic ischaemia
Chronic diarrhea presenting with watery diarrhea that changes in fasting state, with no pus/blood/ fatty stool
Most likely causes
How to differentiate between causes?
Secretory - Persists with fasting
Endocrine tumours: VIPoma, carcinoid syndrome, Zollinger-Ellison syndrome
Bile salt malabsorption
Laxative abuse
Osmotic - Stops with fasting
Lactase deficiency
Osmotic laxative
(Malabsorption)
Motility
IBS
Metabolic: hyperthyroidism
Chronic watery diarrhea
+ steatorrhoea
+ weight loss
+ nutritional deficiency
Most likely causes
Malabsorptive: small bowel diseases, gut resection, bacterial overgrowth, pancreatic diseases
Enteropathy: celiac disease, short gut syndrome, Crohn’s disease
Pancreatic insufficiency: chronic pancreatitis, CA pancreas, CF
Drug-induced diarrhea
Most common causative drugs?
□ Acid-suppressing agents: antacids (esp Mg-containing), H2RA, PPI
□ Alcohol
□ Antibiotics
□ Caffeine: coffee, tea, cola
□ Sorbitol/mannitol: dietectic food, gums, mints (osmotic diarrhoea)
□ Others: β-blocker, NSAID/5-ASA, colchicine, misoprostol, theophylline
Outline P/E for chronic diarrhea
General:
- Dehydration: fluid and electrolyte depletion
- Nutritional status/ weight loss/ vitamin deficiency: Malabsorptive causes
Differentials:
- Hyperthyroidism causing hyper-motility: goitre, thyrotoxic signs
- IBD causing inflammation: episcleritis/uveitis, oral ulcers, arthritis, skin rashes, flushing
- Crohn’s or CA colorectal causing inflammation: PR exam
Signs of toxicity
- Fever
- Abdominal distension, peritoneal signs
First-line blood and stool investigations for chronic diarrhea
Blood tests:
- CBC: anaemia, leukocytosis, eosinophilia, thrombocytosis
- APR: ESR, CRP
- LFT: albumin (malabsorption, protein-losing enteropathy)
- RFT: electrolyte disturbance, hydration
- Serology:
→ AutoAb for IBD: p-ANCA (UC), ASCA (CD)
→ Serum Ig level: hypogammaglobulinaemia → recurrent GE
→ ± HIV Ab if noted lymphopenia - TFT for hyperthyroidism
Stool tests:
- Occult blood**
- Na, K for osmolal gap
- pH
- Leucocytes, microbiology**
- Fecal calprotectin
Differentials of eosinophilia
- Neoplasm
- Allergy
- Collagen vascular diseases
- Parasite infestation
- Eosinophilic gastroenteritis