Bacterial Pathogenicity and Toxins
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Questions and Answers

What is the primary mechanism by which endotoxin LPS causes damage?

  • By disrupting the host cell's membrane structure
  • By forming pores in the host cell membrane
  • By triggering a massive production of pro-inflammatory cytokines (correct)
  • By mimicry, inducing an inappropriate immune response

    • Which of the following is NOT a characteristic of endotoxin LPS?

  • Heat stable
  • Poorly antigenic
  • Highly antigenic (correct)
  • Produced by Gram negative bacteria

    • What is the function of Lipid A in endotoxin LPS?

  • To form pores in the host cell membrane
  • To bind to LPS Binding Protein (LBP) (correct)
  • To activate TLR4 receptors
  • To recognize macrophages and monocytes

    • What is the primary difference between Smooth LPS and Rough LPS?

    <p>The length of the O-antigen</p> Signup and view all the answers

    Which of the following is NOT a type of toxin produced by bacteria?

    <p>Cytokine</p> Signup and view all the answers

    What is the role of CD14 receptors in the inflammatory response to endotoxin LPS?

    <p>To recognize TLR4 receptors</p> Signup and view all the answers

    What is the mechanism by which cholera toxins cause an increase in adenylate cyclase activity?

    <p>By releasing the A region of the toxin through the membrane</p> Signup and view all the answers

    Which disease is associated with a type III secretion system that targets Rho signaling proteins?

    <p>Plague</p> Signup and view all the answers

    What is the function of YopH in the type III secretion system of Yersinia pestis?

    <p>Dephosphorylating tyrosine residues</p> Signup and view all the answers

    What is the origin of the type III secretion system in Yersinia pestis?

    <p>Flagellum</p> Signup and view all the answers

    What is the mechanism by which type IV secretion systems transfer DNA into host cells?

    <p>By injecting DNA via a bacteriophage-like mechanism</p> Signup and view all the answers

    What is the origin of the type IV secretion system in Agrobacterium?

    <p>Pili</p> Signup and view all the answers

    What is the result of the 'cytokine storm' induced by endotoxaemia?

    <p>Septic shock</p> Signup and view all the answers

    What is the mechanism of action of the ST exotoxin?

    <p>It activates the intracellular catalytic domain to produce cGMP from GTP</p> Signup and view all the answers

    What is the result of the non-specific activation of T cells by superantigens?

    <p>Polyclonal activation and weak antiviral activity</p> Signup and view all the answers

    What is the mechanism of action of botulinum toxin?

    <p>It prevents excitatory transmitter vesicles from fusing with the synaptic membrane</p> Signup and view all the answers

    What is the mechanism of action of tetanus toxin?

    <p>It stops the release of inhibitory transmitters</p> Signup and view all the answers

    What is the organisational structure of the anthrax toxin?

    <p>A2B</p> Signup and view all the answers

    What is the result of the action of diphtheria toxin?

    <p>Inhibition of protein synthesis</p> Signup and view all the answers

    What is the mechanism of toxin translocation in diphtheria toxin?

    <p>Via toxin translocation in acidic conditions</p> Signup and view all the answers

    What is the clinical use of botulinum toxin?

    <p>Cosmetic treatment, such as Botox</p> Signup and view all the answers

    What is the result of the action of superantigens?

    <p>Polyclonal activation of T cells</p> Signup and view all the answers

    What is the primary component of the small intestine that is affected in coeliac disease?

    <p>All of the above</p> Signup and view all the answers

    What is the genetic predisposition associated with coeliac disease?

    <p>HLA B8 tissue type</p> Signup and view all the answers

    What is the most common gastrointestinal symptom of coeliac disease?

    <p>Diarrhea</p> Signup and view all the answers

    What is the primary antibody used to diagnose coeliac disease?

    <p>IgA antibodies to transglutaminase</p> Signup and view all the answers

    What is the primary method of diagnosing coeliac disease?

    <p>Blood tests for antibodies</p> Signup and view all the answers

    What is the primary extra-intestinal symptom of coeliac disease?

    <p>Anaemia</p> Signup and view all the answers

    What is the percentage of coeliac disease patients that can be cured by gluten restriction?

    <p>95%</p> Signup and view all the answers

    Which of the following is a risk associated with coeliac disease?

    <p>Lymphoma and adenocarcinoma of the small bowel</p> Signup and view all the answers

    What is the name of the camera used for non-invasive inspection of the small intestine?

    <p>Pillcam Camera</p> Signup and view all the answers

    What is the age of onset for Crohn's disease?

    <p>26 years</p> Signup and view all the answers

    What is the name of the inflammatory bowel disease that is more common in females?

    <p>Crohn's disease</p> Signup and view all the answers

    What is the name of the procedure that can protect against ulcerative colitis?

    <p>Appendicectomy</p> Signup and view all the answers

    What is the name of the vitamin deficiency that can lead to bleeding tendency in coeliac disease?

    <p>Vitamin K deficiency</p> Signup and view all the answers

    What is the name of the condition that can occur in patients with coeliac disease who experience malabsorption?

    <p>All of the above</p> Signup and view all the answers

    What is the name of the inflammatory bowel disease that affects the entire digestive tract?

    <p>Crohn's disease</p> Signup and view all the answers

    What is the name of the treatment used to improve the quality of life for patients with Crohn's disease?

    <p>Both medical and surgical therapy</p> Signup and view all the answers

    Which of the following is a common presentation of colon cancer on the right colon?

    <p>Anaemia</p> Signup and view all the answers

    What is the dental relevance of carcinoma in the colon?

    <p>Tooth decay and gum disease due to anaemia</p> Signup and view all the answers

    Which of the following functional bowel disorders can mask appendicitis?

    <p>Irritable bowel syndrome</p> Signup and view all the answers

    What is the primary characteristic of Osteoma?

    <p>Unexplained pain relieved by analgesics</p> Signup and view all the answers

    What is a common oral manifestation of ulcerative colitis?

    <p>Tongue coating</p> Signup and view all the answers

    Which of the following is a symptom of IBS-C?

    <p>Bloating and gas</p> Signup and view all the answers

    What is the treatment for diverticular disease?

    <p>High fibre diet and surgery</p> Signup and view all the answers

    What is a cutaneous manifestation of ulcerative colitis?

    <p>Pyoderma gangrenosum</p> Signup and view all the answers

    What is an important aspect of the history in inflammatory bowel disease?

    <p>Family history</p> Signup and view all the answers

    What is a bed-side investigation used to diagnose inflammatory bowel disease?

    <p>Sigmoidoscopy</p> Signup and view all the answers

    What is the first step in treating inflammatory bowel disease?

    <p>Induce remission</p> Signup and view all the answers

    What is a medication used to treat Crohn's disease?

    <p>Cyclosporin</p> Signup and view all the answers

    What is a complication of cyclosporin use in dental management?

    <p>Tenderness and swelling of the gums</p> Signup and view all the answers

    What is a medication used to treat ulcerative colitis?

    <p>Aminosalicylates</p> Signup and view all the answers

    What is an acute indication for surgery in ulcerative colitis?

    <p>Failure of medical treatment for 3 days</p> Signup and view all the answers

    What is a prognosis for ulcerative colitis?

    <p>1/3 single attack, 1/3 relapsing attacks, 1/3 progressively worsen</p> Signup and view all the answers

    What is the effect of long-term systemic corticosteroid therapy on dental treatment?

    <p>Increased risk of infection</p> Signup and view all the answers

    Which of the following is a specific dental lesion/complication that can occur as a result of Crohn's?

    <p>Gingival enlargement</p> Signup and view all the answers

    What is the diet used to combat orofacial granulomatosis?

    <p>Cinnamon-free and Benzoates-free diet</p> Signup and view all the answers

    What is the definition of ulcerative colitis?

    <p>Inflammation of the colon with backwash involvement of the terminal ileum</p> Signup and view all the answers

    What is the potential aetiology of ulcerative colitis?

    <p>Dysregulated interaction between mucosal immunology and intestinal microflora</p> Signup and view all the answers

    What is the symptom of ulcerative colitis characterized by?

    <p>Painless bloody diarrhea with mucus</p> Signup and view all the answers

    What is the complication of ulcerative colitis?

    <p>Colorectal cancer</p> Signup and view all the answers

    What is the eye manifestation that can occur with inflammatory bowel diseases?

    <p>Uveitis</p> Signup and view all the answers

    What is the liver/biliary manifestation that can occur with inflammatory bowel diseases?

    <p>Sclerosing cholangitis</p> Signup and view all the answers

    In which inflammatory bowel disease do kidney stones occur?

    <p>Crohn's disease</p> Signup and view all the answers

    What percentage of Salmonella infections lead to bacteremia?

    <p>5-10%</p> Signup and view all the answers

    Why are antibiotics advised against in treating Salmonella?

    <p>They prolong the carriage of the organism in the convalescent phase</p> Signup and view all the answers

    What is the primary method of diagnosing Salmonella infection?

    <p>Laboratory test detecting Salmonella bacteria in stool, body tissue, or fluids</p> Signup and view all the answers

    What is the primary source of Staphylococcus aureus infection?

    <p>Cooked food not stored at 4°C or frozen immediately</p> Signup and view all the answers

    What is the incubation period for Staphylococcus aureus infection?

    <p>1/2-8 hours</p> Signup and view all the answers

    What is the primary symptom of Staphylococcus aureus infection?

    <p>Nausea</p> Signup and view all the answers

    What is the duration of symptoms for Staph.aureus infections?

    <p>1-2 days</p> Signup and view all the answers

    What is the mechanism by which Bacillus cereus survives boiling?

    <p>By forming spores</p> Signup and view all the answers

    What is the most common species of Shigella in developed countries?

    <p>Shigella sonnei</p> Signup and view all the answers

    What is the treatment for Shigellosis?

    <p>Rehydration only</p> Signup and view all the answers

    What is the source of Cryptosporidiosis?

    <p>Infected cattle</p> Signup and view all the answers

    What type of parasite causes Giardiasis?

    <p>Flagellate protozoan</p> Signup and view all the answers

    What is the primary method of diagnosing Clostridium difficile infection?

    <p>Sigmoidoscopy</p> Signup and view all the answers

    What is the mechanism of action for Clostridium perfringens infection?

    <p>Heat-resistant spores survive in contaminated foods</p> Signup and view all the answers

    What is the most common virus that causes viral gastroenteritis in under 3-year-olds?

    <p>Rotavirus</p> Signup and view all the answers

    What is the primary group at risk for Amoebic dysentery?

    <p>People living in the Indian subcontinent and Africa</p> Signup and view all the answers

    What is the frequent cause of infantile gastroenteritis?

    <p>Viral gastroenteritis</p> Signup and view all the answers

    What is the primary treatment for Giardiasis?

    <p>Metronidazole</p> Signup and view all the answers

    What is the primary way to prevent foodborne illnesses?

    <p>All of the above</p> Signup and view all the answers

    What is the treatment for Cryptosporidiosis?

    <p>No specific treatment</p> Signup and view all the answers

    What is the primary risk group for gastroenteritis?

    <p>All of the above</p> Signup and view all the answers

    What is the incubation period for Shigellosis?

    <p>12-96 hours</p> Signup and view all the answers

    What is the primary symptom of Amoebic dysentery?

    <p>Severe diarrhoea with blood and mucus in stool</p> Signup and view all the answers

    What is the primary treatment for Clostridium difficile infection?

    <p>All of the above</p> Signup and view all the answers

    What is the primary way to acquire Amoebic dysentery?

    <p>Eating food contaminated with cysts</p> Signup and view all the answers

    What is the primary location where Amoebic dysentery is most common?

    <p>Indian subcontinent and Africa</p> Signup and view all the answers

    What is the primary mechanism by which Vibrio cholerae causes diarrhoea?

    <p>By producing toxin that stimulates the release of chloride ions</p> Signup and view all the answers

    What is the typical duration of symptoms for Enterohemorrhagic E coli (EHEC)?

    <p>5-10 days</p> Signup and view all the answers

    What is the primary mechanism of action of Enterotoxigenic E coli (ETEC)?

    <p>Production of toxin that stimulates the release of chloride ions</p> Signup and view all the answers

    What is the primary mechanism by which Helicobacter pylori causes chronic gastritis?

    <p>Production of toxin that stimulates the release of gastric acid</p> Signup and view all the answers

    What is the primary mechanism of action of Enteroinvasive E coli (EIEC)?

    <p>Invasion of the intestinal epithelial cells</p> Signup and view all the answers

    What is the primary mechanism by which Listeria monocytogenes causes infection?

    <p>Invasion of the intestinal epithelial cells</p> Signup and view all the answers

    What is the primary mechanism of action of Enteropathogenic E coli (EPEC)?

    <p>Local destruction of intestinal epithelial cells</p> Signup and view all the answers

    What is the primary mechanism by which C.botulinum causes infection?

    <p>Production of toxin that inhibits the release of acetylcholine</p> Signup and view all the answers

    What is the primary mechanism of action of Vibrio cholerae toxin?

    <p>Stimulation of the release of chloride ions</p> Signup and view all the answers

    What is the primary mechanism by which Helicobacter pylori causes gastroduodenal ulceration?

    <p>Production of toxin that stimulates the release of gastric acid</p> Signup and view all the answers

    What percentage of patients experience recurrent infection with Campylobacter gastroenteritis?

    <p>25%</p> Signup and view all the answers

    What is the typical duration of symptoms for Campylobacter gastroenteritis?

    <p>2-10 days</p> Signup and view all the answers

    Which of the following is a risk group for complications with Campylobacter gastroenteritis?

    <p>Pregnant women</p> Signup and view all the answers

    What is the typical incubation period for Salmonella spp?

    <p>12-72 hours</p> Signup and view all the answers

    What is the source of Salmonella?

    <p>Contaminated food and water</p> Signup and view all the answers

    What is a post-infectious complication of Campylobacter gastroenteritis?

    <p>All of the above</p> Signup and view all the answers

    What is the primary reason why the stomach has a limited number of microorganisms?

    <p>Low pH and enzymes</p> Signup and view all the answers

    Which of the following microorganisms is NOT typically found in the small intestine?

    <p>Escherichia coli</p> Signup and view all the answers

    What is the most common cause of acute gastrointestinal illness?

    <p>Infection</p> Signup and view all the answers

    Which of the following bacteria is NOT a common cause of gastroenteritis?

    <p>Staphylococcus epidermidis</p> Signup and view all the answers

    What is the characteristic shape of Campylobacter bacteria?

    <p>Curved</p> Signup and view all the answers

    Which of the following symptoms is NOT typically associated with Campylobacter gastroenteritis?

    <p>Rash</p> Signup and view all the answers

    Study Notes

    Bacterial Pathogenicity

    • The ability of bacteria to cause damage
    • Involves the production of toxins, which can be categorized into three types: endotoxins, exotoxins, and superantigens

    Endotoxins

    • Produced by Gram-negative bacteria
    • Heat-stable and poorly antigenic
    • Consist of four components: O-antigen, outer core, inner core, and lipid A
    • There are three types of LPS: smooth, semi-rough, and rough, with rough LPS being the most potent

    Exotoxins

    • Produced by Gram-positive and Gram-negative bacteria
    • Can be classified into two categories: membrane-acting exotoxins and intracellular exotoxins
    • Examples of membrane-acting exotoxins:
      • Phospholipase (C. perfringens, Listeria, C. albicans)
      • Small toxins (ST, stable toxin) activates guanylin receptor to raise cyclic GMP
      • Proteases
      • Superantigens
    • Mechanism of action of membrane-acting exotoxins:
      1. Attaches to receptors
      2. Enzymes digest the membrane
      3. Pores form to allow ingress/egress of various factors
      4. These factors perturb signaling

    Intracellular Exotoxins

    • Examples:
      1. Neurotoxins
      2. Enterotoxins
    • Mechanism of action:
      1. Cell binding
      2. Membrane translocation
      3. Enzymatic action

    AB Toxins

    • Consist of two components: A (active) fragment and B (binding) fragment
    • Examples of diseases with AB toxin organization:
      1. Diphtheria
      2. Tetanus
      3. Botulinum
    • Diseases with AB5 organization:
      1. Cholera
      2. Shiga
    • Disease with A2B organization:
      1. Anthrax

    Neurotoxins

    • Causes diseases such as:
      1. Botulinum
      2. Tetanus
    • Mechanism of action of tetanus toxin:
      • Stops release of inhibitory transmitters, so signal is never turned off
    • Mechanism of action of botulinum toxin:
      1. Prevents excitatory transmitter vesicles from fusing with the synaptic membrane
      2. No release of neurotransmitter
      3. Signal therefore stops

    Diphtheria

    • Symptoms:
      1. Inflamed throat
      2. Diptheric membrane in throat
      3. Fever
    • Mechanism of action:
      • Blocks EF2, preventing protein extension
    • Regions of the diphtheria toxin:
      1. Active region (A)
      2. Receptor binding region (B)
      3. Endosome insertion region (T)

    Botulinum

    • Symptoms:
      1. Muscle weakness
      2. Excess sweating
      3. Dry mouth
      4. Parkinson's
    • Clinical use:
      • Botox

    Type III and Type IV Secretion Systems

    • Diseases associated with type III and type IV secretion systems:
      1. Plague (Yersinia pestis)
      2. Typhoid (Salmonella typhi)
      3. Shigellosis (Shigella flexneri)
    • Mechanism of type III secretion (in Yersinia):
      1. Bacteria protrudes into each cell and releases:
        • YopE, which inactivates Rho (key signaling protein) to act on cytoskeleton
        • YopT, a protease that attacks Rho
        • YopH, a powerful phosphotyrosine phosphatase
        • YopO, a threonine serine kinase
        • YopM, which goes into the nucleus and blocks dephosphorylation
        • YopP/J, which acetylates kinases to inactivate them and induces apoptosis
    • Mechanism of type IV secretion:
      1. DNA is injected via the bacteriophage
      2. Incorporated into the genome of the organism
      3. Mutates and is used in the organism

    Note: The study notes are written in a concise and engaging manner, focusing on key facts with context.

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    Description

    Learn about bacterial pathogenicity, types of toxins, and their effects on the human body. This quiz covers endotoxins, exotoxins, and more.

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