BLOCK 15 WEEK 1 Flashcards
Gastroenteritis
Gastroenteritis broadly refers to inflammation of the stomach and intestines. It can be caused by a variety of bacterium, viruses or parasites.
- Bacteria that cause it:
Staphylococcus aureus: usually found in cooked meats and cream products. - Bacillus cereus: mainly found in reheated rice.
-Clostridium perfringens: usually found in reheated meat dishes or cooked meats.
-Clostridium difficile: an important cause in healthcare environments, often caused by antibiotics
-Campylobacter
-E.coli including E.coli 0157 (which can cause haemolytic uraemic syndrome)
-Salmonella
-Shigella
Viral causes:
- Rotavirus: most common cause of infantile gastroenteritis
Norovirus: most common cause of viral infectious gastroenteritis in all ages in England and Wales
Adenoviruses: commonly cause infections of the respiratory system but can also cause gastroenteritis, particularly in children.
Parasites:
- Cryptosporidium
-Entamoeba
histolytica
-Giardia intestinalis
-Schistosoma
Symptoms typical
Viral Gastroenteritis:
- Watery diarrhea, nausea and vomiting, low grade fever
Bacterial Gastroenteritis:
- Diarrohea is watery or bloody, vomiting and a moderate to high grade fever
Management
- Avoid food that caused it and handwashing
FLUID REPLACEMENT:
- ORT (oral rehydration therapy) - mild dehydration
- IVF (intravenous fluids) for more severe dehydration
- Antiemetics - to alleviate nausea and diarrhea
- Antibiotic therapy- in severe cases or if immunosuppressed like elderly. Antibiotics rarely help and make E coli 0157 worse
- Bland diet - minimise dairy and high fibre foods to minimise gastrointestinal irritation
NORAVIRUS
Noroviruses cause abrupt onset, usually short lived GI upset 24-48 hours after innoculation.
It is typically self limiting in healthy people but can cause pre-renal acute kidney injury in the frail.
Strict handwashing with soap and warm water are essential steps in limiting the spread in institutions such as hospitals, nursing homes, and cruise ships.
Host defence against GI infection
Peritonitis
Peritonitis refers to the inflammation of the peritoneum, typically caused by perforation of a hollow viscus (rupture of a abdominal organ) or an infection.
The primary signs and symptoms include abdominal rigidity, rebound tenderness, fever, vomiting, tachycardia, and hypotension.
Clostridium Difiicile
Infection is associated with repeated use of antibiotics, proton-pump inhibitors (e.g., omeprazole) and healthcare settings.
C. difficile produces spores, which are released in faeces. The spores can survive on contaminated surfaces and hands, helping it spread to others.
It may colonise the intestines without causing any symptoms or issues. When antibiotics interrupt the normal intestinal microbiome, C. difficile can proliferate and get out of control. It can produce toxins, particularly toxin A (enterotoxin) and toxin B (cytotoxin), which cause symptoms and complications.
Antibiotics most associated with C.diifcile
Clindamycin
Ciprofloxacin (and other fluoroquinolones)
Cephalosporins
Carbapenems (e.g., meropenem)
Presentation
Colonisation is usually asymptomatic.
Infection presents with diarrhoea, nausea and abdominal pain.
Severe infection with colitis can present with:
Dehydration
Systemic symptoms (e.g., fever, tachycardia and hypotension)
Diagnosis
Diagnosis is based on stool samples. Stools can be tested for:
C. difficile antigen (specifically glutamate dehydrogenase)
A and B toxins (by PCR or enzyme immunoassay)
The antigen test shows whether C. difficile is present but not whether it is producing toxins. The antigen is the initial screening test and is followed up with tests for toxins if C. difficile is identified.
Management
Management is with supportive care and oral antibiotics. The options are:
-Oral vancomycin (first-line)
-Oral fidaxomicin (second-line)
Patients need to be isolated until 48 hours after the last episode of diarrhoea. There is a high recurrence rate.
Faecal microbiota transplantation is an option for recurrent cases. The stool microbiome from a donor is transferred to the patient via capsules, colonoscopy or enema.
Complications: Pseudomembranous colitis
Pseudomembranous colitis is characterised by inflammation in the large intestine, with yellow/white plaques that form pseudomembranes on the inner surface of the bowel wall. It is seen during a colonoscopy and confirmed with biopsies to examine the histology.
Toxic megacolon
Toxic megacolon is a complication of severe inflammation in the large intestine and involves dilation of the colon. Patients with toxic megacolon are very unwell and have a high risk of bowel rupture. Treatment involves supportive care and surgical resection of the affected bowel.
Additional complications
Additional complications include bowel perforation and sepsis.
SIBO ( small intestine bacterial overgrowth)
occurs when there is an abnormal increase in the overall bacterial population in the small intestine — particularly types of bacteria not commonly found in that part of the digestive tract. This condition is sometimes called blind loop syndrome.
small intestinal bacterial overgrowth (SIBO) commonly results when a circumstance — such as surgery or disease — slows the passage of food and waste products in the digestive tract, creating a breeding ground for bacteria. The excess bacteria often cause diarrhea and may cause weight loss and malnutrition.
Symptoms of SIBO
READ UP ON COEILIAC DISEASE
READ UP ON INFLAMMATORY BOWEL DISEASE
Different types of mucosa associated lymphatic tissue:
MALTL: is tissue where you would find huge amounts of lymphocytes. These include:
- NALT ( nasal associated lymphatic tissue)
- BALT ( Bronchus- associated lymphatic tissue)
- GALT (gut- associated lymphatic tissue)
-
Layers of the GI tract
The mucosa is the inner most layer of the GI tract made up of:
- Epithelium
- Lamina Propria
- Muscularis mucosa
- Big masses of GALT in GI tract is called Peyers Patches
Peyers Patches
ANTI-INFLAMMATORY DRUGS FOR IBD
INFLAMMATION OF THE BOWEL
- Acute: infective causes
- Chronic: coeliac and inflammatory bowel disease
Nutritional Deficiency
A
Diarrhea contributes to malnutrition through reduction in food intake, decrease in absorption of nutrients, and increase in catabolism of nutrient reserves.
Malabsorption
