Microbiology & Parasitology: Infection Chain
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Questions and Answers

What term describes the state of being free from living pathogenic microorganisms?

  • Cross-contamination
  • Asepsis (correct)
  • Infection
  • Sterilization

    • Virulence refers to the ability of a microorganism to avoid the host's immune defenses.

    False

    Name one source of infection that originates from within the host.

    Endogenous

    The process of destroying all microorganisms and pathogens is known as ____.

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

    Match the types of agents with their descriptions:

    <p>Biological agent = Living organisms that invade the host Chemical agent = Substances that interact with the body Physical agent = Environmental factors causing disease Infectious disease = Pathologic events from microorganism invasion</p> Signup and view all the answers

    Which of the following is a common vector for transmitting diseases?

    <p>All of the above</p> Signup and view all the answers

    A susceptible host is any person that is at the highest risk for infection.

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

    What are the common pathways through which microorganisms enter the body?

    <p>Respiratory tract, gastrointestinal tract, genitourinary tract, broken skin, transplants, transplacental.</p> Signup and view all the answers

    The __________ is the most common vector for diseases such as malaria and dengue.

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

    Match the following age groups with their susceptibility to infections:

    <p>Very Young = Usually more susceptible Very Old = Usually more susceptible Older Children = Less susceptible Young Adults = Less susceptible</p> Signup and view all the answers

    Which organism is responsible for causing syphilis?

    <p>Treponema pallidum</p> Signup and view all the answers

    HIV can be transmitted through infected water.

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

    Name the virus that is spread through the bite of infected mosquitoes.

    <p>Zika virus</p> Signup and view all the answers

    Clostridium ________ causes food poisoning.

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

    Which of the following pathogens can cause dysentery?

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

    Match the following infectious agents with their sources:

    <p>Hepatitis B = Blood and body fluids Rabies = Bite from infected animal Salmonella = Raw meat and unpasteurized milk Measles = Airborne respiratory droplets</p> Signup and view all the answers

    Clostridium tetani is transmitted through contaminated water.

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

    Identify one waterborne disease commonly transmitted through consumption of contaminated water.

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

    Which of the following diseases is caused by a bacterium?

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

    Tuberculosis is caused by a virus.

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

    Name one multidrug-resistant microorganism mentioned.

    <p>Methicillin-resistant staphylococcus aureus (MRSA)</p> Signup and view all the answers

    The bacterium that commonly causes gastritis is __________.

    <p>Helicobacter pylori</p> Signup and view all the answers

    Which organism is NOT typically associated with food poisoning?

    <p>Listeria monocytogenes</p> Signup and view all the answers

    What is the primary causative organism for ear infections?

    <p>Streptococcus pneumoniae</p> Signup and view all the answers

    Match the infections with their causative organisms:

    <p>Pneumonia = Streptococcus pneumoniae Sinusitis = Haemophilus influenzae Food poisoning = Campylobacter jejuni Eye infections = Chlamydia trachomatis</p> Signup and view all the answers

    The virus that can lie dormant in a cell and reactivate later is known as __________.

    <p>varicella-zoster virus</p> Signup and view all the answers

    Which type of flora is always present in the body and offers benefits?

    <p>Endogenous flora</p> Signup and view all the answers

    Transient flora can survive on the skin for more than 24 hours.

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

    Name one benefit of the resident flora in the gastrointestinal tract.

    <p>Prevents the overgrowth of harmful microorganisms.</p> Signup and view all the answers

    An example of a normal flora bacterium found in the mouth is __________.

    <p>Streptococcus mutans</p> Signup and view all the answers

    Match the body areas to their corresponding commensal organisms:

    <p>Mouth &amp; Teeth = Streptococcus pneumoniae Throat = Candida Skin = Escherichia coli Bowel = Staphylococci</p> Signup and view all the answers

    What factor can compromise an individual’s immunity against their own normal flora?

    <p>Debilitating diseases</p> Signup and view all the answers

    Exogenous flora are microorganisms that are normally present in the body.

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

    What is the consequence of normal flora moving to a site they are not usually associated with?

    <p>They can cause infections, such as pneumonia from Staphylococcus aureus migrating from the upper respiratory tract.</p> Signup and view all the answers

    What is the primary method to prevent the spread of microorganisms?

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

    The portal of exit is where the infectious agent enters the host organism.

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

    Identify the susceptible host in the provided scenario.

    <p>The second patient with a Foley catheter</p> Signup and view all the answers

    The infectious agent responsible for the diarrhea in the first patient was __________.

    <p>Escherichia coli</p> Signup and view all the answers

    Match the elements of the chain of infection with their descriptions:

    <p>Infectious Agent = Pathogen causing disease Reservoir = Where the pathogen lives Portal of Exit = Way for pathogen to leave the reservoir Mode of Transmission = How the pathogen is spread Portal of Entry = Access point for pathogen to enter new host Susceptible Host = At risk for infection</p> Signup and view all the answers

    Which of the following actions could break the chain of infection in the scenario?

    <p>Washing hands before assisting the second patient</p> Signup and view all the answers

    Sterilization eliminates all microorganisms, including spores.

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

    List the six processes involved in the chain of infection in sequential order.

    <p>Infectious Agent, Reservoir, Portal of Exit, Mode of Transmission, Portal of Entry, Susceptible Host</p> Signup and view all the answers

    Study Notes

    Microbiology & Parasitology - Source and Chain of Infection

    • Infection is the invasion of body tissue by microorganisms and subsequent growth.
    • Asepsis is the state of being free from living pathogenic microorganisms capable of causing diseases.
    • Cross-contamination is the transmission of infectious microorganisms from one person or object to another.

    Learning Outcomes

    • Students will be able to define infection.
    • Students will be able to describe agents causing infection.
    • Students will be able to explain sources of infection (endogenous and exogenous).
    • Students will be able to describe the chain of infection.
    • Students will be able to discuss how to break the chain of infection.

    Terminology

    • Infectious disease: Pathological events resulting from invasion and multiplication of microorganisms in a host.
    • Sterilization: Process that destroys all microorganisms and pathogens.
    • Virulence: Degree to which a microorganism can cause or invade a host.

    Agent Causing Infection

    • Biological agents: Living organisms that invade the host (bacteria, viruses, fungi, parasites).
    • Chemical agents: Substances that interact with the body (food additives, medications, industrial chemicals).
    • Physical agents: Environmental factors capable of causing disease (heat, light, noise, radiation, machinery).

    Types of Microorganisms

    • Bacteria: Single-celled microorganisms; most common infection cause; causes diseases like cholera, diphtheria, dysentery, plague, pneumonia, tuberculosis, typhoid, and typhus.
    • Viruses: Microorganisms that replicate inside living cells; causes diseases like measles, mumps, chickenpox, tuberculosis; some viruses cause warts.
    • Fungi: Tiny primitive organisms feeding on living plants, animals, and decaying organic matter; cause infection known as mycosis (ringworm, candidiasis); some are opportunistic pathogens.
    • Protozoa: Single-celled organisms; reproduce by binary fission; live in moist habitats (e.g., fresh water, soil); some cause diarrhea, such as amoebiasis.
    • Helminths (Parasites): Large, multicellular organisms; some are free-living and some are parasitic; cause gastrointestinal tract infections; transmitted from hand to mouth.

    Sources of Infection

    • Endogenous: From the individual's own body (normal flora).
      • Resident flora: Always present; beneficial if staying in their associated sites; prevent harmful microorganisms' overgrowth, and produce vitamins (e.g., Vitamin K, B12). May cause disease if they're in the wrong location due to immune compromise.
      • Transient flora: Survive on skin less than 24 hours; easily removed by soap and water; acquired during contact with contaminated areas like the mouth, nose, perineal, genital, and anal areas.
    • Exogenous: From outside the individual's body.
      • Human sources: Sexually transmitted organisms (syphilis, gonorrhea, HIV, Hepatitis B&C), exposure to blood and body fluids (needle sticks).
      • Animal/vector: Zika virus, rabies, anthrax (through handling animals/spores), avian influenza (bird flu) (through contact with infected birds).
      • Animal products: Salmonella, E. coli, campylobacter, listeria (from raw meat, unpasteurized milk, raw eggs).
      • Water: Waterborne diseases (e.g., diarrhea, caused by protozoa and bacteria in sewage-contaminated water).
      • Food: Foodborne illnesses (e.g., salmonella, E. coli, listeria).
      • Environment: Soil and air can be contaminated (e.g., tetanus, botulism, measles, mumps, diphtheria).

    Chain of Infection

    • Infectious agent: Microorganisms causing disease.
    • Reservoir: Places where microorganisms live and reproduce (e.g., contaminated food, water, human/animal waste, infected person, animal, inanimate objects).
    • Portal of exit: Routes by which microorganisms leave the reservoir (e.g., respiratory tract, gastrointestinal tract, genitourinary tract, broken skin, blood, vaginal discharge).
    • Mode of transmission: Methods by which microorganisms travel from a reservoir to a susceptible host (e.g., airborne, contact, vector, vehicle/fomite).
    • Portal of entry: Entry points into a susceptible host (e.g., respiratory tract, gastrointestinal tract, skin, genitourinary tract, transplants, transplacental).
    • Susceptible host: Individuals at risk for infection (e.g., elderly, immunocompromised, certain occupations).

    Breaking the Chain of Infection

    • Identifying infected individuals and treating them appropriately.
    • Maintaining good personal hygiene amongst potentially contaminated sources.
    • Using disinfectants and appropriate sterilization for inanimate objects to reduce pathogens.
    • Controlling the route of transmission; Use of precaution through PPE (gown, mask, eye shields, and gloves).
    • Educating clients/others on infection prevention.
    • Treating underlying conditions that affect immune response to prevent infection.

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    Topic 6. Sources and Chain of Infection PDF

    Description

    This quiz covers the key concepts of infection, including definitions, sources, and the chain of infection. Students will learn about asepsis, cross-contamination, and the ways to break the chain of infection. Gain a thorough understanding of infectious diseases and their impact on health.

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