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Questions and Answers
What is the primary function of bacterial capsules?
What is the primary function of bacterial capsules?
Which pathogen uses Type IV pili for attachment?
Which pathogen uses Type IV pili for attachment?
What component is produced by Mycobacterium tuberculosis that aids in immune evasion?
What component is produced by Mycobacterium tuberculosis that aids in immune evasion?
Which of the following is a characteristic of fimbriae produced by some Streptococcus species?
Which of the following is a characteristic of fimbriae produced by some Streptococcus species?
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Enterotoxigenic E. coli (ETEC) uses which type of adhesin to promote diarrhea?
Enterotoxigenic E. coli (ETEC) uses which type of adhesin to promote diarrhea?
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What happens to pH levels when cariogenic bacteria proliferate due to carbohydrate fermentation?
What happens to pH levels when cariogenic bacteria proliferate due to carbohydrate fermentation?
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Which characteristic of Candida albicans contributes to its virulence?
Which characteristic of Candida albicans contributes to its virulence?
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How does the herpes simplex virus evade the immune system?
How does the herpes simplex virus evade the immune system?
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What role do cytotoxic T cells play in the host's response to pathogens?
What role do cytotoxic T cells play in the host's response to pathogens?
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What is a key characteristic of pathogens that successfully survive in a host environment?
What is a key characteristic of pathogens that successfully survive in a host environment?
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What structure do bacteria use to adhere to host cells?
What structure do bacteria use to adhere to host cells?
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What is the function of adhesins in bacterial infections?
What is the function of adhesins in bacterial infections?
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Which of the following is NOT considered a mechanism of virulence in bacteria?
Which of the following is NOT considered a mechanism of virulence in bacteria?
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Which pathogen is associated with Protein F adhesin?
Which pathogen is associated with Protein F adhesin?
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What type of motility is associated with Class IV pili?
What type of motility is associated with Class IV pili?
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Which factor helps bacteria resist physical removal from host cells?
Which factor helps bacteria resist physical removal from host cells?
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What type of adhesin is associated with Streptococcus mutans?
What type of adhesin is associated with Streptococcus mutans?
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Which type of bacterial adhesion allows for a 'slingshot' movement on host cells?
Which type of bacterial adhesion allows for a 'slingshot' movement on host cells?
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What is the term for the presence of pus-forming bacteria in the blood?
What is the term for the presence of pus-forming bacteria in the blood?
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Which virulence factor enables Staphylococcus aureus to evade phagocytosis?
Which virulence factor enables Staphylococcus aureus to evade phagocytosis?
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What best describes antigenic drift in viruses?
What best describes antigenic drift in viruses?
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What role do fimbriae play in the function of Porphyromonas gingivalis?
What role do fimbriae play in the function of Porphyromonas gingivalis?
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Which of the following is NOT a characteristic of Streptococcus mutans related to cariogenicity?
Which of the following is NOT a characteristic of Streptococcus mutans related to cariogenicity?
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How do pathogens typically destroy T lymphocytes?
How do pathogens typically destroy T lymphocytes?
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Which of the following factors is directly associated with the pathogenicity of Streptococcus mutans?
Which of the following factors is directly associated with the pathogenicity of Streptococcus mutans?
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What is the primary function of kinases produced by some pathogens?
What is the primary function of kinases produced by some pathogens?
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What role do exoenzymes play in pathogens?
What role do exoenzymes play in pathogens?
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What is true about endotoxins?
What is true about endotoxins?
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Which of the following describes exotoxins?
Which of the following describes exotoxins?
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What is the consequence of high endotoxin concentrations in the blood?
What is the consequence of high endotoxin concentrations in the blood?
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Which category of exotoxins specifically targets cells and disrupts membranes?
Which category of exotoxins specifically targets cells and disrupts membranes?
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What term describes the presence of toxins in the bloodstream?
What term describes the presence of toxins in the bloodstream?
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What is the mechanism through which exotoxins damage cells?
What is the mechanism through which exotoxins damage cells?
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Which of the following describes the ability of a pathogen to produce toxins?
Which of the following describes the ability of a pathogen to produce toxins?
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Study Notes
Virulence Factors
- Adhesion - bacterial strategy to adhere to host cell surface. Prevents physical removal and allows colonization.
- Pili - hair-like structures on bacterial surface. Allows bacterial movement along host cell surface.
- Fimbriae - bristle-like bacterial appendages which aid in adhesion.
- Capsules - Some bacteria produce capsules. Aid in adhesion and immune evasion.
- Bacterial Cell Walls - Contain adhesins (surface proteins/glycoproteins) which bind to host cell surface receptors for adhesion.
Specific Pathogens
- Streptococcus pyogenes - utilizes Protein F.
- Streptococcus mutans – dental caries. Utilizes Adhesin P1 to adhere to teeth.
- Neisseria gonorrhoeae - utilizes Type IV pili to adhere to urethral epithelial cells.
- Enterotoxigenic E. coli (ETEC) - utilizes Type I fimbriae to adhere to intestinal epithelial cells.
Evasion of Phagocytosis (Antiphagocytic Factors)
- Streptococcus – M protein in Fimbriae alters surface to inhibit phagocytosis.
- Mycobacterium tuberculosis - produces mycolic acid in cell wall to deter killing mechanisms within phagocytes.
Exoenzymes
- Extracellular enzymes secreted by bacteria.
- Invade deeper tissues for colonization.
- Specific to particular tissue structures.
- Enable bacterial invasion, support growth and evade the immune system.
Toxins
- Biological poisons produced by pathogens.
- Endotoxins - produced by gram-negative bacteria.
- Exotoxins - produced by gram-positive bacteria and some gram-negative bacteria.
Terminology to Describe Pathogens in Bloodstream
- Bacteraemia - presence of bacteria in the blood.
- Pyaemia - presence of pus-forming bacteria in the blood.
- Toxaemia - presence of toxins in the blood.
- Septicaemia - multiplying bacteria in the blood.
Virulence Factors Promoting Infection
- Coagulase - enables coating with fibrin clots, preventing phagocytosis.
- Kinases - stimulate digestion of fibrin clots for pathogen escape.
- Antigenic Variation - surface proteins are altered to avoid immune recognition.
- Leukocidins - destroy phagocytes.
- Intracellular Position - pathogens reside inside host cells, evading immune defenses.
Viral Virulence
- Adhesins - mediated by viral capsid or membrane envelope. Enables interaction with specific cell receptors.
- Antigenic Variation - antigenic drift and shift.
- Antigenic Drift - minor changes in spike proteins due to point mutations.
- Antigenic Shift - major changes in spike proteins due to gene re-assortment.
Virulence Factors in Oral Health
- Porphyromonas Gingivalis - utilizes fimbriae to modify immune responses and gingipains (proteases) to break down periodontal structural proteins.
- Streptococcus Mutans - caries. Utilizes adhesion, acidogenicity, and acid tolerance.
Herpes Simplex Virus
- Hides in neurons and non-neuronal cells.
- Reactivates during low immune resistance.
Candida Albicans
- Opportunistic human fungal infections.
- Exoenzymes - secreted aspartyl proteases (Sap proteins).
- Adhesins - aid in attachment.
- Pleomorphism - adapts to environmental changes.
Conclusion
- Pathogens evolve to increase virulence and avoid immune responses.
- Constantly interact with host cells in a dynamic process.
- New virulence factors are countered by host defenses.
- Pathogens produce 'escape mutations' to avoid immune targeting.
- Most successful pathogens take advantage of the host without causing immediate death.
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