Infection/infectious diseases
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Questions and Answers

Which of the following best describes 'infectivity' in the context of infectious diseases?

  • The severity of the disease caused by a microorganism.
  • The microorganism's ability to infect and cause disease in the host.
  • The ability of a pathogen to induce an immune response.
  • The ability of a pathogen to invade and multiply in the host. (correct)

    • Which of the following is NOT a typical portal of entry for a pathogenic microorganism?

  • Ingestion of contaminated food or water.
  • Direct contact with a contaminated surface.
  • Inhalation of airborne droplets.
  • Injection through a vaccine. (correct)

    • Which of the following host factors is LEAST likely to increase the risk of infection?

  • Regular exercise. (correct)
  • Recent antibiotic use.
  • Malnutrition.
  • Advanced Age.

    • What is the primary difference between exotoxins and endotoxins in bacterial infections?

    <p>Exotoxins are actively secreted by the bacteria, while endotoxins are released upon bacterial cell lysis. (B)</p> Signup and view all the answers

    What is the role of mobile appendages, such as flagella, in bacterial pathogenesis?

    <p>To enable the bacteria to move and spread within the host. (C)</p> Signup and view all the answers

    Which of the following is the most direct consequence of antimicrobial resistance?

    <p>Ineffectiveness of antibiotics against bacterial infections. (D)</p> Signup and view all the answers

    What is a key mechanism by which bacteria develop resistance to antibiotics?

    <p>Developing enzymes that inactivate the antibiotic. (D)</p> Signup and view all the answers

    A patient is prescribed antibiotics for a bacterial infection. Which of the following potential complications should the healthcare provider discuss with the patient?

    <p>Destruction of beneficial gut flora and potential for secondary infections. (B)</p> Signup and view all the answers

    Regarding the pathogenesis of infection, what immediately follows the penetration of initial defenses by a pathogen?

    <p>Multiplication and formation of a colony. (A)</p> Signup and view all the answers

    Which of the following is the most accurate description of 'bacteremia?'

    <p>The presence of bacteria in the bloodstream. (A)</p> Signup and view all the answers

    Which of the following factors differentiates communicability from virulence in the context of infectious diseases?

    <p>Communicability describes the potential for transmission, while virulence defines the degree of harm caused by the microorganism. (D)</p> Signup and view all the answers

    Which of the following scenarios exemplifies a microorganism's invasion mechanism?

    <p>A virus enters a host cell via receptor-mediated endocytosis. (A)</p> Signup and view all the answers

    How does bacteremia differ fundamentally from septicemia?

    <p>Bacteremia indicates presence of bacteria in the blood, whereas septicemia indicates bacterial growth in the blood. (B)</p> Signup and view all the answers

    Considering portals of entry, which of the following infections is LEAST likely to occur through inhalation?

    <p><em>Streptococcus pyogenes</em> causing pharyngitis (B)</p> Signup and view all the answers

    Which of the following best describes the relationship between environmental sanitation and the risk of infection?

    <p>Poor environmental sanitation creates a reservoir for pathogens, increasing the likelihood of transmission. (C)</p> Signup and view all the answers

    A bacterium inhibits phagocytosis, produces toxins, and demonstrates antimicrobial resistance. Which of the following strategies would MOST effectively address all three virulence mechanisms simultaneously?

    <p>Employing bacteriophages to selectively infect and destroy the resistant bacteria. (B)</p> Signup and view all the answers

    What is the fundamental difference between exotoxins and endotoxins?

    <p>Exotoxins are secreted proteins, while endotoxins are structural components of the bacterial cell wall. (D)</p> Signup and view all the answers

    How do anti-phagocytic factors contribute to bacterial virulence?

    <p>They impair the ability of immune cells to engulf and destroy bacteria. (D)</p> Signup and view all the answers

    What is the significance of bacterial movement from initial defenses to lymph nodes and the blood system in the pathogenesis of bacterial infections?

    <p>It enables systemic spread and potential sepsis. (A)</p> Signup and view all the answers

    Which of the following mechanisms is LEAST likely to contribute to antimicrobial resistance in bacteria?

    <p>Increased permeability of the bacterial cell wall to the antibiotic. (B)</p> Signup and view all the answers

    Flashcards

    Pathogenicity

    Microorganism’s ability to infect and cause disease in the host.

    Virulence

    Microorganism’s ability to cause severe disease or harm to the host.

    Infectivity

    Ability of pathogen to invade and multiply in the host.

    Communicability

    Ability to spread the disease from one individual to another.

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    Immunogenicity

    Ability of pathogens to induce an immune response.

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    Bacteremia

    Presence of bacteria in the bloodstream.

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    Portal of entry

    Route by which a pathogenic microorganism infects the host.

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    Exotoxins

    Toxins released by bacteria, often causing disease.

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    Antimicrobial resistance

    Ability of bacteria to resist effects of antibiotics.

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    Gram stain reaction

    A method to classify bacteria based on cell wall composition.

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    Microbial Adherence

    Ability of a microorganism to latch onto and gain entrance into its host.

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    Invasion

    Mechanism by which the microorganism invades/enters the host.

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    Bacterial Etiology

    The cause of infection specifically related to bacteria.

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    Bacterial Mediators

    Factors like toxins and enzymes produced by bacteria that aid in infection.

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    Antimicrobial Resistance Causes

    Reasons bacteria develop resistance to antibiotics, such as overuse or sub-therapeutic dosing.

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    Portal of Entry Examples

    Various routes by which pathogenic microorganisms infect hosts, including inhalation and bites.

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    Inflammatory Response

    Body's reaction to an infection which involves immune activation and inflammation.

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    Gram Negative Bacilli

    A category of bacteria characterized by their negative reaction to Gram staining, often more resistant.

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    Sepsis

    A severe infection leading to systemic inflammatory response syndrome (SIRS) and potential organ failure.

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    Vaccines Role

    Stimulates immune response to prevent infections.

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    Study Notes

    Infection & Immune Dysfunction

    • Infection is the invasion and multiplication of pathogenic microorganisms within a host.
    • Pathogenicity: A microorganism's ability to infect and cause disease in a host.
    • Microbial Adherence: The ability of a microorganism to attach to and enter a host.
    • Invasion: The mechanism by which a microorganism enters and invades a host.
    • Communicability: The ability of a disease to spread from one person to another.
    • Virulence: The ability of a microorganism to cause severe disease or harm to a host.
    • Immunogenicity: Ability of pathogens to evoke an immune response.
    • Infectivity: Ability of a pathogen to invade and multiply in a host.
    • Bacteremia: Presence of bacteria in the blood.
    • Septicemia: Growth of bacteria in the blood.

    Infection

    • Portal of entry: Route by which a pathogenic microorganism infects the host.
      • Direct contact
      • Inhalation
      • Ingestion
      • Bites of an animal or insect

    Risk Factors

    • Environmental:
      • Sanitation
      • Air quality
      • Living conditions
      • Climate
    • Host:
      • Malnutrition
      • Age
      • Chronic illness
      • Stress
      • Immunosuppression
      • Recent antibiotic use

    Bacterial Infection

    Etiology: Bacteria

    • Inhibit phagocytosis
    • Produce toxins
    • Single-celled:
      • Cocci
      • Bacilli
      • Vibrio
      • Spirilla
    • Oxygen requirement:
      • Aerobic
      • Anaerobic
    • Gram stain reaction:
      • Gram +
      • Gram -
      • Acid-fast

    Bacterial Infection Mediators

    • Toxins
      • Exotoxins: proteins that contribute to disease
      • Endotoxins: lipopolysaccharides that trigger inflammation
    • Enzymes
    • Endospores
    • Anti-phagocytic factors
    • Mobile appendages (e.g., flagella, pili)
    • Antimicrobial resistance

    Bacterial Infection Pathogenesis

    • Penetrate initial defenses
    • Multiply and create a colony
    • Overwhelm lymph nodes and blood system
    • Stimulate immune response
    • Move in the body via fluids
    • Bacteremia, sepsis, and systemic inflammatory response syndrome (SIRS)

    Pathogenesis & Clinical Manifestations

    • Streptococcus pneumoniae (can cause pneumonia, meningitis, and other infections)
    • Streptococcus pyogenes (can cause strep throat, scarlet fever, and other infections)
    • Staphylococcus aureus (can cause skin infections, pneumonia, and other infections)
    • Gram-negative bacilli (e.g., E. coli, Klebsiella)
    • Haemophilus influenzae (can cause meningitis and other infections)
    • Clostridium difficile (causes severe diarrhea)
    • Salmonella (causes food poisoning and other infections)
    • Shigella (causes dysentery)

    Treatment Implications

    • Antibiotics
      • Complications: Antimicrobial resistance (due to overuse and inappropriate use)
      • Destruction of vaginal and GI flora (leading to opportunistic infections)
      • Side effects: Anaphylactic shock (severe allergic reaction)
    • Stimulate immune response: Vaccines (to prevent infections)

    Antimicrobial Resistance

    • Causes:
      • Sub-therapeutic dosing
      • Excessive antibiotic use
    • Resistance mechanisms:
      • Enzymes inactivating antibiotics; antibiotic inactivation
      • Creating targets no longer susceptible to antibiotics; altered antibiotic targets
      • Preventing entry into cells
      • Actively pumping antibiotics out of cells; antibiotic efflux

    Antimicrobial resistance pathogenesis

    • Chance mutation in the bacteria
    • Proliferation of mutated bacteria
    • Survive antibiotic exposure
    • Examples – Vancomycin-resistant Enterococci (VRE), Methicillin-resistant Staphylococcus aureus (MRSA)

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