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 (B)

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 (D)</p> Signup and view all the answers

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

<p>False (B)</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 (B)</p> Signup and view all the answers

HIV can be transmitted through infected water.

<p>False (B)</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 (B)</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 (B)</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 (B)</p> Signup and view all the answers

Tuberculosis is caused by a virus.

<p>False (B)</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 (C)</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 (A)</p> Signup and view all the answers

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

<p>False (B)</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 (D)</p> Signup and view all the answers

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

<p>False (B)</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 (B)</p> Signup and view all the answers

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

<p>False (B)</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 (C)</p> Signup and view all the answers

Sterilization eliminates all microorganisms, including spores.

<p>True (A)</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

Flashcards

Infection

Invasion of body tissue by microorganisms and their growth there

Biological Agent

Living organisms that invade a host, causing disease (e.g., bacteria, viruses, fungi)

Bacteria

Single-celled microorganisms that can cause disease, are common, and reduce organ function.

Asepsis

A state free of disease-causing microorganisms (pathogens).

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Cross-contamination

Spread of infection from one person or object to another.

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Bacterial Infections

Diseases caused by bacteria, some of which have caused major historical epidemics.

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Bacterial Meningitis

Brain infection caused by various bacteria like Streptococcus pneumoniae, Neisseria meningitides, and Haemophilus influenzae

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Pneumonia Cause

Lung infection usually caused by Streptococcus pneumoniae or Haemophilus influenzae; other causes include atypical bacteria like Mycoplasma pneumoniae.

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Tuberculosis Cause

Lung infection caused by bacterium Mycobacterium tuberculosis.

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MRSA

A type of staphylococcus bacteria resistant to methicillin, causing various infections.

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Viral Infection

An infection caused by a virus, which invades cells and replicates within them.

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Viral Replication

The process by which a virus multiplies within a host cell.

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Virus Replication

Viral genetic material takes over the cell and makes more viruses, which are released to infect new cells.

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Endogenous Flora

Microorganisms that are normally present in the body and are considered part of the body's natural defense system.

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Resident Flora

Microorganisms that permanently reside in the body and usually have a beneficial role in maintaining health.

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Transient Flora

Microorganisms that are temporarily present in the body and can be removed with proper hygiene.

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Normal Flora Benefits

Resident flora can provide benefits, such as preventing the growth of harmful microbes, synthesizing vitamins, and stimulating immune responses.

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Normal Flora Risks

If resident flora relocate to a site where they aren't normally found, they can cause infections.

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Compromised Immunity

When the body's ability to fight off infections is weakened, normal flora can cause disease.

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Exogenous Flora

Microorganisms that originate from the external environment and can cause infections when they enter the body.

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Exogenous Flora Sources

Sources of exogenous flora include the environment, contaminated objects, and other people.

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Vectors of disease

Living organisms that transmit infectious diseases between humans or from animals to humans. Examples include flies, mites, fleas, and ticks.

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Mosquito transmission

Mosquitoes are common vectors that can transmit malaria and dengue by injecting salivary fluid during biting.

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Entry route of pathogens

Microorganisms usually enter the body through the same route they used to leave the source, such as the respiratory tract, gastrointestinal tract, genitourinary tract, or broken skin.

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Susceptible host

A person at risk of getting an infection.

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Compromised host

A person with weakened defenses who is more likely to get an infection.

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Syphilis Cause

Caused by the bacterium Treponema pallidum, transmitted through sexual contact.

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Gonorrhea Cause

Caused by the bacterium Neisseria gonorrhoeae, transmitted through sexual contact.

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Hepatitis B and C Transmission

Spread through exposure to infected blood and body fluids, such as through needle stick injuries, mucous membrane contact, and skin exposure.

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Zika Virus Transmission

Spread through the bite of infected mosquitoes.

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Rabies Transmission

Spread through the bite of infected animals, like dogs or wild animals, and broken skin. Can cause inflammation of the brain.

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Anthrax Transmission

Spread through handling infected animals or materials containing anthrax spores, eating infected meat, or breathing in spores.

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Salmonella Infection Source

Spread through contaminated animal products like raw meat, unpasteurized milk, and raw eggs.

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Waterborne Disease Transmission

Transmitted by consuming infected water, often contaminated with sewage.

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Chain of Infection

A sequence of events that must occur for an infection to spread. It involves a pathogen, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host.

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Infectious Agent

The microorganism that causes the infection (e.g., bacteria, virus, fungi, parasites).

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Reservoir

The place where the infectious agent lives and multiplies (e.g., human body, animal, contaminated water, soil).

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Portal of Exit

The way the infectious agent leaves the reservoir (e.g., respiratory droplets, feces, blood, urine).

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Mode of Transmission

The method of transferring the infectious agent from the reservoir to the susceptible host (e.g., direct contact, airborne droplets, contaminated objects).

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Portal of Entry

The way the infectious agent enters the susceptible host (e.g., respiratory tract, mucous membranes, broken skin).

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Break the Chain

To interrupt the chain of infection, we must prevent one or more links in the chain from happening. This can be achieved by using methods like handwashing, disinfection, isolation, and vaccination.

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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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