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?

The length of the O-antigen Signup and view all the answers

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

Cytokine Signup and view all the answers

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

To recognize TLR4 receptors Signup and view all the answers

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

By releasing the A region of the toxin through the membrane Signup and view all the answers

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

Plague Signup and view all the answers

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

Dephosphorylating tyrosine residues Signup and view all the answers

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

Flagellum Signup and view all the answers

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

By injecting DNA via a bacteriophage-like mechanism Signup and view all the answers

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

Pili Signup and view all the answers

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

Septic shock Signup and view all the answers

What is the mechanism of action of the ST exotoxin?

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

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

Polyclonal activation and weak antiviral activity Signup and view all the answers

What is the mechanism of action of botulinum toxin?

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

What is the mechanism of action of tetanus toxin?

It stops the release of inhibitory transmitters Signup and view all the answers

What is the organisational structure of the anthrax toxin?

A2B Signup and view all the answers

What is the result of the action of diphtheria toxin?

Inhibition of protein synthesis Signup and view all the answers

What is the mechanism of toxin translocation in diphtheria toxin?

Via toxin translocation in acidic conditions Signup and view all the answers

What is the clinical use of botulinum toxin?

Cosmetic treatment, such as Botox Signup and view all the answers

What is the result of the action of superantigens?

Polyclonal activation of T cells Signup and view all the answers

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

All of the above Signup and view all the answers

What is the genetic predisposition associated with coeliac disease?

HLA B8 tissue type Signup and view all the answers

What is the most common gastrointestinal symptom of coeliac disease?

Diarrhea Signup and view all the answers

What is the primary antibody used to diagnose coeliac disease?

IgA antibodies to transglutaminase Signup and view all the answers

What is the primary method of diagnosing coeliac disease?

Blood tests for antibodies Signup and view all the answers

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

Anaemia Signup and view all the answers

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

95% Signup and view all the answers

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

Lymphoma and adenocarcinoma of the small bowel Signup and view all the answers

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

Pillcam Camera Signup and view all the answers

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

26 years Signup and view all the answers

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

Crohn's disease Signup and view all the answers

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

Appendicectomy Signup and view all the answers

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

Vitamin K deficiency Signup and view all the answers

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

All of the above Signup and view all the answers

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

Crohn's disease 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?

Both medical and surgical therapy Signup and view all the answers

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

Anaemia Signup and view all the answers

What is the dental relevance of carcinoma in the colon?

Tooth decay and gum disease due to anaemia Signup and view all the answers

Which of the following functional bowel disorders can mask appendicitis?

Irritable bowel syndrome Signup and view all the answers

What is the primary characteristic of Osteoma?

Unexplained pain relieved by analgesics Signup and view all the answers

What is a common oral manifestation of ulcerative colitis?

Tongue coating Signup and view all the answers

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

Bloating and gas Signup and view all the answers

What is the treatment for diverticular disease?

High fibre diet and surgery Signup and view all the answers

What is a cutaneous manifestation of ulcerative colitis?

Pyoderma gangrenosum Signup and view all the answers

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

Family history Signup and view all the answers

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

Sigmoidoscopy Signup and view all the answers

What is the first step in treating inflammatory bowel disease?

Induce remission Signup and view all the answers

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

Cyclosporin Signup and view all the answers

What is a complication of cyclosporin use in dental management?

Tenderness and swelling of the gums Signup and view all the answers

What is a medication used to treat ulcerative colitis?

Aminosalicylates Signup and view all the answers

What is an acute indication for surgery in ulcerative colitis?

Failure of medical treatment for 3 days Signup and view all the answers

What is a prognosis for ulcerative colitis?

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

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

Increased risk of infection 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?

Gingival enlargement Signup and view all the answers

What is the diet used to combat orofacial granulomatosis?

Cinnamon-free and Benzoates-free diet Signup and view all the answers

What is the definition of ulcerative colitis?

Inflammation of the colon with backwash involvement of the terminal ileum Signup and view all the answers

What is the potential aetiology of ulcerative colitis?

Dysregulated interaction between mucosal immunology and intestinal microflora Signup and view all the answers

What is the symptom of ulcerative colitis characterized by?

Painless bloody diarrhea with mucus Signup and view all the answers

What is the complication of ulcerative colitis?

Colorectal cancer Signup and view all the answers

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

Uveitis Signup and view all the answers

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

Sclerosing cholangitis Signup and view all the answers

In which inflammatory bowel disease do kidney stones occur?

Crohn's disease Signup and view all the answers

What percentage of Salmonella infections lead to bacteremia?

5-10% Signup and view all the answers

Why are antibiotics advised against in treating Salmonella?

They prolong the carriage of the organism in the convalescent phase Signup and view all the answers

What is the primary method of diagnosing Salmonella infection?

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

What is the primary source of Staphylococcus aureus infection?

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

What is the incubation period for Staphylococcus aureus infection?

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

What is the primary symptom of Staphylococcus aureus infection?

Nausea Signup and view all the answers

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

1-2 days Signup and view all the answers

What is the mechanism by which Bacillus cereus survives boiling?

By forming spores Signup and view all the answers

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

Shigella sonnei Signup and view all the answers

What is the treatment for Shigellosis?

Rehydration only Signup and view all the answers

What is the source of Cryptosporidiosis?

Infected cattle Signup and view all the answers

What type of parasite causes Giardiasis?

Flagellate protozoan Signup and view all the answers

What is the primary method of diagnosing Clostridium difficile infection?

Sigmoidoscopy Signup and view all the answers

What is the mechanism of action for Clostridium perfringens infection?

Heat-resistant spores survive in contaminated foods Signup and view all the answers

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

Rotavirus Signup and view all the answers

What is the primary group at risk for Amoebic dysentery?

People living in the Indian subcontinent and Africa Signup and view all the answers

What is the frequent cause of infantile gastroenteritis?

Viral gastroenteritis Signup and view all the answers

What is the primary treatment for Giardiasis?

Metronidazole Signup and view all the answers

What is the primary way to prevent foodborne illnesses?

All of the above Signup and view all the answers

What is the treatment for Cryptosporidiosis?

No specific treatment Signup and view all the answers

What is the primary risk group for gastroenteritis?

All of the above Signup and view all the answers

What is the incubation period for Shigellosis?

12-96 hours Signup and view all the answers

What is the primary symptom of Amoebic dysentery?

Severe diarrhoea with blood and mucus in stool Signup and view all the answers

What is the primary treatment for Clostridium difficile infection?

All of the above Signup and view all the answers

What is the primary way to acquire Amoebic dysentery?

Eating food contaminated with cysts Signup and view all the answers

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

Indian subcontinent and Africa Signup and view all the answers

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

By producing toxin that stimulates the release of chloride ions Signup and view all the answers

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

5-10 days Signup and view all the answers

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

Production of toxin that stimulates the release of chloride ions Signup and view all the answers

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

Production of toxin that stimulates the release of gastric acid Signup and view all the answers

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

Invasion of the intestinal epithelial cells Signup and view all the answers

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

Invasion of the intestinal epithelial cells Signup and view all the answers

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

Local destruction of intestinal epithelial cells Signup and view all the answers

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

Production of toxin that inhibits the release of acetylcholine Signup and view all the answers

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

Stimulation of the release of chloride ions Signup and view all the answers

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

Production of toxin that stimulates the release of gastric acid Signup and view all the answers

What percentage of patients experience recurrent infection with Campylobacter gastroenteritis?

25% Signup and view all the answers

What is the typical duration of symptoms for Campylobacter gastroenteritis?

2-10 days Signup and view all the answers

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

Pregnant women Signup and view all the answers

What is the typical incubation period for Salmonella spp?

12-72 hours Signup and view all the answers

What is the source of Salmonella?

Contaminated food and water Signup and view all the answers

What is a post-infectious complication of Campylobacter gastroenteritis?

All of the above Signup and view all the answers

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

Low pH and enzymes Signup and view all the answers

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

Escherichia coli Signup and view all the answers

What is the most common cause of acute gastrointestinal illness?

Infection Signup and view all the answers

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

Staphylococcus epidermidis Signup and view all the answers

What is the characteristic shape of Campylobacter bacteria?

Curved Signup and view all the answers

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

Rash 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.