Infectious Disease and Microorganisms
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Questions and Answers

What is the term used to describe the microflora that lives in harmony with the human body?

  • Commensal flora (correct)
  • Normal pathogens
  • Mutualistic microbiota
  • Parasitic organisms

    • Which of the following is an example of mutualism?

  • Virus that infects the skin
  • Fungus that lives on the skin
  • Bacteria that produce vitamins beneficial to humans (correct)
  • Bacteria that cause disease in the intestines

    • What is the term used to describe an interaction in which a colonizing organism benefits and the host sustains injury?

  • Parasitic (correct)
  • Commensalism
  • Mutualism
  • Symbiotic

    • What is the characteristic of prions that makes them resistant to antimicrobial agents?

    <p>They lack reproductive and metabolic functions</p> Signup and view all the answers

    Which of the following is a possible transmission mechanism of prions?

    <p>Cannibalism</p> Signup and view all the answers

    What is the characteristic of Rickettsia?

    <p>They are obligate intracellular parasites</p> Signup and view all the answers

    Which of the following is NOT a characteristic of Rickettsia, Chlamydia, Coxiella, and Mycoplasma?

    <p>They have a rigid cell membrane</p> Signup and view all the answers

    What is the term used to describe the normal microflora that lives in the human body?

    <p>Resident microbiota</p> Signup and view all the answers

    What is the term used to describe the presence and multiplication of a living organism within a host, resulting in injury to the host?

    <p>Infection</p> Signup and view all the answers

    Which of the following terms is used to describe microorganisms that are not harmful to humans?

    <p>Microflora</p> Signup and view all the answers

    What is the term used to describe the ability of an organism to enter, multiply, and survive in a host?

    <p>Infectivity</p> Signup and view all the answers

    Which of the following is an example of an opportunistic pathogen?

    <p>An organism that produces disease only when the host's health and immunity are severely compromised</p> Signup and view all the answers

    What is the term used to describe the disease-producing potential of an invading organism?

    <p>Virulence</p> Signup and view all the answers

    Which of the following is a type of interaction between the host and colonizing microorganisms?

    <p>Commensalism</p> Signup and view all the answers

    What is the term used to describe free-living organisms that obtain nutrition from dead or decaying organic materials in the environment?

    <p>Saprophytes</p> Signup and view all the answers

    What is the term used to describe an organism that is capable of supporting the nutritional and physical growth requirements of another organism?

    <p>Host</p> Signup and view all the answers

    Which of the following is an example of a biofilm?

    <p>Dental plaque</p> Signup and view all the answers

    What is the main function of flagella in bacteria?

    <p>To enable bacteria to move from one place to another</p> Signup and view all the answers

    Which type of toxin is released when gram-negative bacteria die?

    <p>Endotoxin</p> Signup and view all the answers

    What is the main function of capsule in bacteria?

    <p>To protect bacteria from ingestion by macrophages</p> Signup and view all the answers

    Which of the following is an example of an enzyme produced by bacteria?

    <p>Hemolysin</p> Signup and view all the answers

    How do gram-negative bacteria protect themselves from the effects of antibiotics?

    <p>By having an outer membrane that protects them</p> Signup and view all the answers

    What enables bacteria to survive in difficult environmental conditions?

    <p>Spores</p> Signup and view all the answers

    How do bacteria develop resistance to drugs?

    <p>By mutations in their genes</p> Signup and view all the answers

    What is the primary mode of transmission in airborne transmission?

    <p>Carried on evaporated droplets or dust particles</p> Signup and view all the answers

    What is the typical duration of symptoms of Salmonella infection?

    <p>507 days</p> Signup and view all the answers

    Which of the following is an example of a vehicle-borne transmission?

    <p>Contaminated food</p> Signup and view all the answers

    Which of the following bacteria can lead to typhoid fever?

    <p>Salmonella</p> Signup and view all the answers

    What is the term for infections acquired during hospitalization or from a healthcare facility?

    <p>Nosocomial infections</p> Signup and view all the answers

    What is the term for the process by which a pathogen enters the body and gains access to susceptible tissue?

    <p>Portal of Entry</p> Signup and view all the answers

    What is the primary mode of transmission of Shigella infection?

    <p>Fecal-oral route</p> Signup and view all the answers

    Which of the following is an example of a penetration route of infection?

    <p>Abrasions or burns</p> Signup and view all the answers

    What is the typical duration of symptoms of Shigella infection?

    <p>5-7 days</p> Signup and view all the answers

    What is the primary cause of Bacterial Infections of the Urinary Tract?

    <p>E. coli, Pseudomonas aeruginosa, and Klebsiella</p> Signup and view all the answers

    Which of the following is an example of direct contact transmission?

    <p>Sexual contact</p> Signup and view all the answers

    What is the characteristic rash associated with Lyme's disease?

    <p>Bull's-eye rash</p> Signup and view all the answers

    Which of the following is an example of ingestion route of infection?

    <p>Contaminated food or water</p> Signup and view all the answers

    Which of the following is an example of inhalation route of infection?

    <p>Entry of infectious agents through respiratory tract</p> Signup and view all the answers

    What is the most common tick-borne infection in the northern hemisphere?

    <p>Lyme's disease</p> Signup and view all the answers

    What is the characteristic of viruses as pathogens?

    <p>Smallest obligate intracellular pathogen</p> Signup and view all the answers

    Study Notes

    Infectious Disease

    • Infectious disease occurs when microorganisms invade the human body, causing harmful and potentially lethal consequences.
    • Microorganisms can be pathogens or non-pathogens, and all microbes are microorganisms, but not all microorganisms are microbes.

    Microorganisms and Terminology

    • Microorganisms are organisms so small they are invisible to the naked eye and can only be seen with a microscope.
    • Infection: the presence and multiplication within a host of another living organism with subsequent injury to the host.
    • Infectivity: the ability of an organism to enter, multiply, and survive in a host.
    • Host: any organism capable of supporting the nutritional and physical growth requirements of another organism.
    • Colonization: the act of establishing a presence within a host.
    • Virulence: the disease-producing potential of an invading organism.
    • Pathogen: an organism so virulent that it is rarely found in the absence of disease.
    • Microflora: a multitude of non-harmful bacteria inhabiting the internal and external exposed surfaces of the human body.
    • Saprophytes: free-living organisms that obtain nutrition from dead or decaying organic materials in the environment.
    • Opportunistic Pathogen: an organism that produces an infectious disease only when the health and immunity of the host have been severely compromised.

    Types of Interactions Between Host and Colonizing Microorganisms

    • Commensalism: the multitude of non-harmful bacteria inhabiting the internal and external exposed surfaces of the human body acquire survival needs from the host, but the host is not adversely affected by this relationship.
    • Mutualism: an interaction in which colonizing organism and host both derive benefits.
    • Parasitic: an interaction in which a colonizing organism benefits and the host sustains injury.

    Agents of Infection Disease

    • Prions: protein particles that lack any kind of demonstrable genetic material, can affect other normal proteins and alter them, and aggregate in the brain to form plaques.
    • Rickettsia, Chlamydia, Coxiella, Mycoplasma: these organisms combine the characteristics of viruses and bacteria, are obligate intracellular pathogens like viruses, and most produce a rigid peptidoglycan cell wall, reproduce asexually, and contain RNA and DNA like bacteria.

    Modes of Transmission

    • Airborne transmission: occurs when microbes are transmitted by air currents across long distances (more than one meter).
    • Vector-borne transmission: animals, or biting arthropods transmit microbes to humans.
    • Vehicle-borne transmission: occurs when infection is transmitted by a contaminated source (vehicle).
    • Portal of Entry: the process by which a pathogen enters the body and gains access to susceptible tissue.
    • Penetration: any disruption in the integrity of the body's surface barrier (skin or mucous membrane) is a potential site for invasion.
    • Direct contact: pathogens are transmitted directly from infected tissue or secretions to exposed, intact mucous membranes.
    • Ingestion: entry of infectious agent occurs through oral cavity and GI tract.
    • Inhalation: entry of infectious agents through respiratory tract.

    Bacterial Defences

    • Biofilm: some bacteria secrete a substance that helps them to attach to other bacteria, cells, or body tissues.
    • Capsule: some bacteria are enclosed in a protective capsule that helps to protect them from ingestion by macrophages.
    • Outer membrane/cell wall: gram-negative bacteria have an outer membrane that protects them from the effects of antibiotics.
    • Spores: some bacteria produce spores that enable them to survive when environmental conditions are difficult.
    • Flagella: long thin filaments that project from a cell wall and enable bacteria to move from one place to another.
    • Antibiotic resistance: bacteria can develop resistance to drugs because their genes can mutate.

    Bacterial Infections

    • Salmonella infection: can lead to typhoid fever, a sometimes deadly disease more common in developing countries.
    • Shigella infection (a.k.a. Shillosis): a common infection in settings where hygiene is poor, spread via the fecal-oral route.
    • Bacterial infections of the urinary tract: affect the urethra, urinary bladder, ureters, and kidneys, commonly caused by E. coli, Pseudomonas aeruginosa, and Klebsiella.

    Viral Infections

    • Viruses are the smallest obligate intracellular pathogens.

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    Infectious Disease Class Notes PDF

    Description

    Learn about the basics of infectious disease, microorganisms, and related terminology. Understand how microorganisms invade the human body and cause harm.

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