Session 9 Flashcards
(24 cards)
Describe the key features of the gut immune response to infection, including the Gut-associated lymphoid tissue (GALT) LO
- What are the main features of innate immunity?
- Physical barriers
- Physiological barriers
- Chemical barriers
- Biological barriers
- • Fast (within seconds)
- Lack of specificity
- Lack of memory
- No change in intensity
- Mucous membranes GI tract
- • Diarrhoea
• Vomiting - • Low pH stomach (1-3)
- Antimicrobial molecules IgA (saliva, mucous membrane )
- Mucus (Mucous membranes)
- Gastric acid + pepsin
- • Normal flora (Non pathogenic microbes)
- Mouth/Throat/GI tract
- Compete with pathogens for attachment sites and resources.
- Produce antimicrobial chemicals
- Synthesize vitamins (K, B12, other B vitamins).
- GALT is the ?
- State the layers of the gut
- New epithelial cells derived from stem cells are constantly produced on the bottom of the intestinal glands, regenerating the epithelium (epithelial cell turnover time is less than one week). Although in these crypts conventional enterocytes are the dominant type of cells, Paneth cells can also be found. These are located at the bottom of the crypts and release a number of ?
- Underneath them, there is an underlying layer of loose connective tissue called lamina propria. There is also lymphatic circulation through the tissue connected to the ?
- Where are payers patches located?
- What is found in payers patches
- What are payers patches covered by?
- Largest collection of lymphoid tissues = mesenteric lymph nodes (MLN) and payers patchers & effector (lamina propria) sites that contain specialized populations of B (IgA) and T cells (IgAþ plasmablasts)
- Image
- antibacterial substances, among them lysozyme, and are thought to be involved in the control of infections.
- mesenteric lymph nodes
- submucosa and extend into mucosa (ileum & distal jejunum but can detected in the juodenum)
- macrophages, dendritic cells, B-lymphocytes, and T-lymphocytes
- Follicle-associated epithelium that contains specialized cells called microfold cells (M cells) which sample antigen directly from the lumen and deliver it to antigen-presenting cells.
The appendix, tonsils and peters patches are all part of GALT. What is their clinical significance.
Appendix – Appendicitis – often caused by lymphoid hyperplasia which then causes stasis which leads to infection. Also caused by faecoliths.
Ileocaecal Lymphatic Tissue – Mesenteric Adenitis – common cause of right iliac fossa pain in children
Peyer’s Patches – Typhoid Fever – inflamed peyer’s patches in terminal ileum due to typhoid fever
Tonsilitis - group a strep
There are approximately 1014 bacteria in the GI Tract, the majority of which are in the colon. This normal flora and has several beneficial roles:
o Synthesise and excrete vitamins
- Vitamin K, Vitamin B12, Thiamine
o Prevent colonisation by pathogens
- Space, Bacteriosides
o Kill non-indigenous bacteria
Bacteriosides
o Stimulate the development of GALT
o Stimulate production of natural antibodies
Complete the table stating the normal microbiota at each of these sites:
Eye, nares, nasopharynx, mouth, stomach, intestine, urethra & vagina
Describe an clinical approach, with regard to history, examination & investigation (Management) of a patient presenting with gastroenteritis
• History taking ->
- inc travel and exposure history
- onset of symptoms
- medications
- signs/symptoms
- other household members? /Any unwell travel companions /contacts? • Pre-travel vaccinations / preventative measures? • Recreational activities? • Healthcare exposure?
• Physical examination to include hydration status -> Mucous membranes
Skin turgor or
Postural Blood pressure
Urinanalysis
• Take appropriate samples and request the right test. Stools -> cultures molecular testing ,microscopy. Certain only relative to certain types of infections
• Supportive treatment +/-antimicrobial treatment. Review with test results -> Fluids oral/IV
Treating with antibiotics is not always necessary and helpful e.g. e.coli 057?
State the important bacterial causes of gastroenteritis LO
Salmonella (Enteriditis & Typhimurium)
Shigella
Campylobacter (C. jejuni & C. coli)
Enterotoxigenic E.coli 0157 (ETEC) traveler’s diarrhea
Transmission
Salmonella (Enteriditis & Typhimurium)
Shigella
Campylobacter (C. jejuni & C. coli)
Enterotoxigenic E.coli 0157 (ETEC) traveler’s diarrhea
investigations and results of investigation
gram negative rods
Signs & symptoms
Salmonella (Enteriditis & Typhimurium)
Shigella
Campylobacter (C. jejuni & C. coli)
Enterotoxigenic E.coli 0157 (ETEC) traveler’s diarrhea
Guillain Barré syndrome = rapid-onset muscle weakness caused by the immune system damaging the peripheral nervous system
btu on internet says cause is unknown
Salmonella (Enteriditis & Typhimurium)
Shigella
Campylobacter (C. jejuni & C. coli)
Enterotoxigenic E.coli 0157 (ETEC) traveler’s diarrhea
Salmonella (Enteriditis & Typhimurium)
Shigella
Campylobacter (C. jejuni & C. coli)
Enterotoxigenic E.coli 0157 (ETEC) traveler’s diarrhea
Treatment & how they look
How to prevent salmonella & shigella
Salmonella:
Proper sewage disposal, correct handling of food, & good personal hygiene.
Shigella:
- Wash hands frequently
- Supervise small children when they wash their hands
- Dispose of soiled diapers properly
- Disinfect diaper-changing areas after use
- _Don’t prepare food for others if you have diarrhea for atleast 48hrs after symptoms
reside_ - Keep children with diarrhea
- home from child care, play groups or school
- Avoid swallowing water from ponds, lakes or untreated pools
- Avoid sexual activity with anyone who has diarrhea or who recently recovered from diarrhea
Clostridium difficile
- Complications
- Why is it a problem in hospital?
- How do we treat?
Cholera
- Transmission
- Structure
- Mast Cells – Fluid loss in Cholera – an infection in the gut which activates the complement system will activate mast cells which release histamine and cause vasodilation and increased vascular permeability which leads to massive fluid loss
- Treatment :
- pseudomembranous colitis, toxic megacolon, perforation of the colon, and sepsis
- Spore forming
- Metronidazole ( if resistant give vancomycin)
stop previous medication
- Poor sanitation -> fecal oral route
2.
- Lipopolysaccharide
- Oral rehydration
- flagella
- proteases which hydrolyse mucus
- pili
- gram negative bacilli
- relatively large (104 - 106 of organisms)
Recognise viral causes of gastroenteritis LO
source of transmission, investigations, incubation, treatment,
Norovirus prevention, infectious dose and structure
Norovirus
• Most common cause of epidemic gastroenteritis • Peak incidence in winter • all ages • Immunity short-lived, reinfections can occur • Outbreaks associated with hospitals, schools, nurseries, restaurants, cruise ships, hotel resorts.
Source of transmission
Investigations
Travel history
transmission
Prevention, infectious dose, viral structure
Incubation period, Average course length of illness, Investigations, Treatment, Prevention, pathogenesis
Treatment, prevention, pathogenesis
invade the epithelium, potentially inducing ulceration. The parasite can further spread to the liver & cause abscesses. In the colon, trophozoites form cysts that pass in the feces.
Consider some additional causes of GI infections describe the key features of Cryptosporidium LO
Transmission, investigation, treatment, prevention
