Podcast
Questions and Answers
Which of the following is primarily related to the adaptive capability of C. albicans?
Which of the following is primarily related to the adaptive capability of C. albicans?
- Pleomorphism (correct)
- Exoenzymes
- Virulence evolution
- Cytotoxic T cells
What is the role of ‘Sap Proteins’ in C. albicans?
What is the role of ‘Sap Proteins’ in C. albicans?
- Secreting hydrolytic enzymes (correct)
- Promoting immune responses
- Inhibiting tissue invasion
- Facilitating adhesion
How do pathogens like C. albicans evolve to avoid immune responses?
How do pathogens like C. albicans evolve to avoid immune responses?
- By increasing adhesion strength
- By producing escape mutations (correct)
- By reducing virulence factors
- By enhancing viral replication
What is the significance of the interaction between pathogens and host cells?
What is the significance of the interaction between pathogens and host cells?
Which statement best describes the most successful pathogens?
Which statement best describes the most successful pathogens?
What defines a primary pathogen?
What defines a primary pathogen?
Which of the following statements about virulence factors is correct?
Which of the following statements about virulence factors is correct?
What does pathogenicity refer to?
What does pathogenicity refer to?
Which type of pathogen is only capable of causing disease under specific conditions, such as when the host is immunocompromised?
Which type of pathogen is only capable of causing disease under specific conditions, such as when the host is immunocompromised?
How does the degree of virulence relate to pathogenicity?
How does the degree of virulence relate to pathogenicity?
Which of the following is NOT considered a virulence factor?
Which of the following is NOT considered a virulence factor?
Select the term that best describes the ability of a pathogen to successfully evade the immune system.
Select the term that best describes the ability of a pathogen to successfully evade the immune system.
Which of the following best summarizes the role of opportunistic pathogens?
Which of the following best summarizes the role of opportunistic pathogens?
What happens if the concentration of endotoxins in the blood is high?
What happens if the concentration of endotoxins in the blood is high?
How are endotoxins inactivated?
How are endotoxins inactivated?
Which of the following best describes exotoxins?
Which of the following best describes exotoxins?
What term describes the presence of toxins in the blood?
What term describes the presence of toxins in the blood?
Which exotoxin category is associated with disrupting cell membranes?
Which exotoxin category is associated with disrupting cell membranes?
What effect does the production of coagulase by Staphylococcus aureus have on the immune response?
What effect does the production of coagulase by Staphylococcus aureus have on the immune response?
In which condition would you find multiplying bacteria in the bloodstream?
In which condition would you find multiplying bacteria in the bloodstream?
Which factor contributes to toxic shock syndrome?
Which factor contributes to toxic shock syndrome?
What is the primary risk of low concentrations of endotoxins?
What is the primary risk of low concentrations of endotoxins?
What role do kinases play in bacterial infection?
What role do kinases play in bacterial infection?
What is the primary function of bacterial adhesins?
What is the primary function of bacterial adhesins?
Which bacterial pathogen is associated with dental caries?
Which bacterial pathogen is associated with dental caries?
How do bacterial capsules contribute to immune evasion?
How do bacterial capsules contribute to immune evasion?
What is the role of fimbrae in some Streptococcus species?
What is the role of fimbrae in some Streptococcus species?
What function do Type IV pili serve for Neisseria gonorrhoeae?
What function do Type IV pili serve for Neisseria gonorrhoeae?
What component does Mycobacterium tuberculosis produce to evade phagocytosis?
What component does Mycobacterium tuberculosis produce to evade phagocytosis?
Which of the following diseases is caused by Enterotoxigenic E. coli?
Which of the following diseases is caused by Enterotoxigenic E. coli?
Which feature aids in the adhesion and resistance to removal of bacteria from host surfaces?
Which feature aids in the adhesion and resistance to removal of bacteria from host surfaces?
What is the main purpose of extracellular enzymes secreted by bacteria?
What is the main purpose of extracellular enzymes secreted by bacteria?
Which bacteria is known to utilize Type 1 fimbriae for pathogen adherence?
Which bacteria is known to utilize Type 1 fimbriae for pathogen adherence?
Which factor is NOT part of the chain of infection?
Which factor is NOT part of the chain of infection?
What does virulence refer to in the context of infectious agents?
What does virulence refer to in the context of infectious agents?
Which factor increases susceptibility to an infectious agent?
Which factor increases susceptibility to an infectious agent?
Molecular Koch’s postulates are used to prove which relationship?
Molecular Koch’s postulates are used to prove which relationship?
How is the dose of an agent related to disease causation?
How is the dose of an agent related to disease causation?
Which of the following is a step in identifying virulence factors?
Which of the following is a step in identifying virulence factors?
Which of the following best describes exposure in the context of disease causation?
Which of the following best describes exposure in the context of disease causation?
What type of culture is typically used to study virulence factors?
What type of culture is typically used to study virulence factors?
Which condition may lead to a weakened immune system?
Which condition may lead to a weakened immune system?
What does the term 'susceptibility' refer to in the context of infectious diseases?
What does the term 'susceptibility' refer to in the context of infectious diseases?
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Study Notes
Terminology
- Pathogen: Any organism that can cause disease in a host.
- Primary Pathogen: Can cause disease in a healthy individual.
- Opportunistic Pathogen: Causes disease in an immunocompromised host.
- Pathogenicity: The ability of a pathogen to cause disease.
- Virulence: The degree or intensity of a pathogen's ability to cause disease.
- Virulence Factors: Mechanisms that contribute to a pathogen's ability to cause damage, invasion, and infectivity.
Chain of Infection
- Agent: Identity of the pathogen, its virulence, and the dose required to cause disease.
- Exposure: How the pathogen is transmitted.
- Susceptibility: Factors that make the host more vulnerable to infection, such as diabetes or immunosuppression.
Virulence Factors and Pathogens
- Streptococcus pyogenes: Causes strep throat, uses Protein F adhesin to attach to respiratory epithelial cells.
- Streptococcus mutans: Contributes to dental caries, utilizes Adhesin P1 to adhere to teeth.
- Neisseria gonorrhoeae: Causes gonorrhoea, uses Type IV pili to attach to urethral epithelial cells.
- Enterotoxigenic E.coli (ETEC): Causes traveller's diarrhea, uses Type 1 fimbriae to attach to intestinal epithelial cells.
- Vibrio cholerae: Causes cholera, utilizes N-methylphenylalanine pili to attach to intestinal epithelial cells.
Mechanisms of Immune Evasion
- Capsules: Prevent phagocytosis by immune cells.
- Aid in adhesion.
- Composition prevents antibody adhesion.
- Size hinders phagocytosis.
- Fimbriae and Cell Walls:
- M Protein (Streptococcus): Alters bacterial surface to inhibit phagocytosis.
- Mycolic Acid (Mycobacterium tuberculosis): Acts as a protective coat to deter killing mechanisms during phagocytosis.
Extracellular Enzymes and Toxins
- Endotoxins:
- Derived from gram-negative bacteria.
- Trigger a systemic inflammatory response.
- Extremely stable and require high temperatures for inactivation.
- Low concentrations induce effective immune response, high concentrations can lead to severe complications like multi-organ failure.
- Exotoxins:
- Potent protein molecules produced by various bacteria, mainly gram-positive.
- Specific in their action and target cells.
- Damage cells through unique molecular mechanisms.
- Heat-sensitive and inactivated by temperatures above 41°C.
- Can be lethal in low concentrations.
Terms Describing Pathogens in Bloodstream
- Bacteraemia: Presence of bacteria in the blood.
- Pyaemia: Pus-forming bacteria in the blood.
- Toxaemia: Presence of toxins in the blood.
- Septicaemia: Multiplying bacteria in the blood.
Further Protection Against Immune System
- Coagulase (Staphylococcus aureus): Triggers fibrin clot formation, preventing phagocytosis and allowing bacteria to persist in the body.
- Kinases: Breakdown fibrin clots, allowing bacteria to spread and escape.
Candida albicans Virulence Factors
- Exoenzymes: Produce hydrolytic enzymes for tissue invasion.
- Adhesins: Promote colonization and invasion.
- Pleomorphism: Adapts to different environments and niches.
Conclusion
- Pathogens continuously evolve to enhance virulence and evade immune responses.
- Production of new virulence factors is countered by the host's immune system.
- Pathogens evolve and produce "escape mutations" to evade immune responses.
- The most successful pathogens are those that can exploit the host without causing immediate death.
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