Questions and Answers
Which of the following is a characteristic of a syndrome?
Which of the following is a local effect of an infection?
Which of the following is a mechanism by which an infectious organism can evade the host's immune system?
Which of the following is an example of an organism's entry and spread in the body?
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Which of the following is NOT a mechanism by which an infectious organism can evade the host's immune system?
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Which of the following is an example of a sign of infection?
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What is the primary characteristic of a persistent infection?
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What is the main difference between latent and chronic persistent infections?
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What is the term for infections acquired in a hospital or medical facility?
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What is the outcome of the balance between microbial replication and spread and the host's ability to respond or resist?
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What is the term for the reactivation of a latent infection?
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Why are nosocomial infections common?
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What is an example of a latent infection?
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What is the outcome of the host's ability to respond or resist microbial replication and spread?
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What is the primary reason normal flora can cause opportunistic infections?
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Which of the following conditions is likely to predispose an individual to opportunistic infections?
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What does the term 'carriers' refer to in the context of infectious diseases?
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Which microorganism is cited as a common cause of urinary tract infections when it ascends the urethra?
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What does 'colonization' imply regarding microorganisms?
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How can antibiotic use lead to yeast infections in the vagina?
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Which statement best describes a pathogen?
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What role does host defense play in preventing opportunistic infections?
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What is the role of sickle cell trait in relation to malaria?
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Which age group is most susceptible to influenza infection?
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What underlying characteristic does NOT increase susceptibility to infections?
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Which condition exemplifies immunodeficiency related to pathogenesis?
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What is a potential consequence of surgical implants in terms of infections?
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Which immune response is notably associated with severe influenza infections?
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HIV long-term non-progressors are best described as individuals who:
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What factor is NOT considered a determinant of pathogenesis related to the host?
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What is the primary factor in immunopathogenesis that leads to cell death during many infections?
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Which of the following best describes the role of Cytotoxic T cells in disease pathology?
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What is a common outcome of antibody-mediated damage in infections like Streptococcus pyogenes?
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In the context of infectious diseases, what do symptoms refer to?
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Which of the following conditions is primarily associated with antibody-mediated complement fixation?
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What is the relationship between exposure, infection, and clinical syndrome in the course of infectious diseases?
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What role does the complement system play in immunopathogenesis, especially in Hepatitis C infections?
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Which of these statements about microbial pathogenesis is accurate?
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Study Notes
Harmful Effects of Flora: Opportunistic Infections
- Caused by non-pathogenic microorganisms that act as pathogens in certain circumstances
- Normal flora can move to other parts of the body and cause infection, e.g. Escherichia coli can ascend urethra and cause urinary tract infections (UTIs)
- Weakened host defense mechanisms (immunocompromised patients) can lead to fungal or bacterial infections, e.g. Candida spp., Aspergillus spp., or Pseudomonas aeruginosa
- Lack of competition from normal flora due to its loss from the body can lead to infections, e.g. vaginal yeast infections due to antibiotic use
Pathogenesis: Basic Definitions and Concepts
- Infection: presence of microorganisms in the body
- Colonisation: growth of new microorganisms on superficial body sites without invading the body
- Carrier: person who harbors a microorganism and can be a source of infection for others
- Pathogen: microorganism capable of causing disease
- Microbial pathogenesis: process by which infection leads to disease
Course of Infectious Diseases
- Organism exposure leads to infection, which can cause a clinical syndrome
- Immunopathogenesis: killing of infected cells by the host immune system can lead to cell death, e.g. cytotoxic T cell mediated attack, antibody-mediated damage to the host, or antibody-mediated complement fixation
Clinical Manifestations of Disease
- Symptoms: subjective features of disease experienced only by the patient
- Signs: objective manifestations of disease that can be observed and measured by others
- Syndrome: group of symptoms and signs characteristic of a disease
- Infections can be asymptomatic (sub-clinical) or symptomatic
Host Response to Infection
- Local effects: inflammation, tissue necrosis, and nasal congestion
- Systemic effects: fever, altered immune response, and muscle pain (myalgia)
Obligatory Steps for Infectious Organisms
- Entry and spread: attach and enter with local or general spread in the body, evading host's primary defenses
- Evasion: evade host's immune system long enough for full cycle in host to be completed
Types of Infections: Based on Outcome
- Acute infection: balance between microbial replication and spread, and the host's ability to respond or resist
- Persistent infection: pathogen is not cleared from the host following primary infection, and remains in tissues of infected individuals
- Latent infection: microorganism persists after initial clearance, and may have asymptomatic or symptomatic reactivation
- Chronic infection: continued production of the infectious organism and immune evasion
Nosocomial Infections
- Definition: any infection acquired in a hospital or medical facility
- Can affect patients and health care workers
- Common due to ease of transmission by staff, patients, or visitors, and imperfect prevention by hand washing
Determinants of Pathogenesis: Host
- Age: infants and elderly are more susceptible to influenza infection
- Underlying characteristics: increase susceptibility, e.g. asthma, obesity, diabetes, or malnutrition
- Genetic variation: e.g. sickle cell trait provides protection to malaria, or HIV long-term non-progressors
- Immunodeficiency: e.g. opportunistic infections in AIDS patients
- Immune response: e.g. "cytokine storm" in influenza infection
- Trauma/surgery/foreign body: e.g. surgical implants make it easier for bacteria to cause infection and more difficult to eradicate it
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Description
This quiz covers the process of how infections lead to disease, including exposure, infection, and clinical syndrome. It also explores immunopathogenesis and the host's immunological response.