Bacterial Nutrition and Pathogenicity
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Questions and Answers

What type of case can present clinical signs and symptoms of an organism?

  • Only domestic pets
  • Humans, animals, and arthropods (correct)
  • Only humans
  • Only mammals

Which of the following is an example of zoonosis?

  • HIV transmitted by blood transfusion
  • Malaria transmitted by mosquitoes
  • Flu transmitted between humans
  • Rabies transmitted by dogs (correct)

What is the role of an organism in a case that presents with clinical signs?

  • It does not have a significant role.
  • It is a pathogen causing symptoms in the host. (correct)
  • It provides immunity to the host.
  • It acts as a carrier without causing illness.

What is one way that anthrax can be transmitted to humans?

<p>Ingesting raw or undercooked meat from infected animals (C)</p> Signup and view all the answers

Which of the following organisms can be a source of zoonotic infections?

<p>Infected livestock and domestic animals (A)</p> Signup and view all the answers

Which organism is identified as a throat carrier?

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

What type of carriers are associated with Staphylococcus aureus?

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

Which of the following is not a blood-borne carrier?

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

Which pathogens are associated with blood carriers?

<p>HIV, HBV, and HCV (D)</p> Signup and view all the answers

Which carrier type is State associated with HIV?

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

Which of the following diseases is NOT primarily spread through droplet infection?

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

What is the maximum distance that droplet infections typically travel?

<p>1 meter (D)</p> Signup and view all the answers

Which condition is least likely to be caused by a droplet infection?

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

Which of the following statements is true regarding droplet infection?

<p>Microbes spread in droplets typically travel less than 1 meter. (B)</p> Signup and view all the answers

Which of these diseases is commonly associated with droplet transmission?

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

What is referred to as the lethal dose in microbiology?

<p>The number of organisms needed to kill 50% of animals (D)</p> Signup and view all the answers

Which of the following best describes virulence factors?

<p>Structures or products that help microorganisms cause disease (C)</p> Signup and view all the answers

What role do virulence factors play in pathogens?

<p>They contribute to the pathogenicity and ability to cause disease (B)</p> Signup and view all the answers

What unit is used to express a lethal dose of toxin?

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

Which of the following statements about virulence factors is incorrect?

<p>They are only present in pathogenic bacteria (D)</p> Signup and view all the answers

What impact does Immunoglobulin A (IgA) protease have on mucous surfaces?

<p>It degrades the secretory IgA, leading to loss of protection. (B)</p> Signup and view all the answers

What bacterium is known to produce coagulase?

<p>Staphylococcus aureus (C)</p> Signup and view all the answers

Which statement about secretory IgA is true regarding its role in the immune system?

<p>It protects mucosal surfaces from pathogen invasion. (A)</p> Signup and view all the answers

What is the consequence of the action of IgA protease on host defenses?

<p>Diminished ability to neutralize pathogens at mucosal surfaces. (C)</p> Signup and view all the answers

How does coagulase contribute to the pathogenicity of Staphylococcus aureus?

<p>By forming clots that protect the bacteria from the immune system. (C)</p> Signup and view all the answers

What are detoxified toxins used for in vaccinations called?

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

What chemical is used to treat toxins in order to create toxoids?

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

What does antigenicity refer to in the context of toxoids?

<p>Capacity to produce antibodies (C)</p> Signup and view all the answers

Why are toxoids considered important for vaccination?

<p>They lose toxicity but retain immune response capability (A)</p> Signup and view all the answers

Which of the following statements about toxoids is correct?

<p>Toxoids retain their capacity to produce antibodies. (D)</p> Signup and view all the answers

Flashcards

Case

A person who carries and shows symptoms of a disease.

Zoonosis

A disease that can be transmitted from animals to humans.

Rabies

A disease spread through the bite of an infected animal, often causing neurological symptoms.

Anthrax

A serious bacterial infection that infects the lungs and can be spread through infected animals.

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Tuberculosis (TB)

A bacterial infection that can be spread through the milk of infected animals, affecting the respiratory system.

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Throat (Oropharyngeal) Carrier

A person who carries the bacteria that causes diphtheria in their throat.

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Nasal/Skin Carrier

A person who harbors Staphylococcus aureus bacteria in their nose or on their skin.

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Blood Carrier (HIV)

A person who carries the virus that causes HIV in their blood.

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Blood Carrier (HBV)

A person who carries the virus that causes hepatitis B in their blood.

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Blood Carrier (HCV)

A person who carries the virus that causes hepatitis C in their blood.

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Droplet Infection

Infection spread through tiny droplets of moisture released when an infected person coughs, sneezes, or talks. These droplets travel short distances, usually less than one meter.

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Tonsillitis

A disease caused by a bacterial infection that affects the tonsils.

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Diphtheria

A serious bacterial infection primarily affecting the respiratory system, characterized by a thick, grayish membrane forming in the throat.

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Meningitis

An inflammation of the meninges, the membranes surrounding the brain and spinal cord, commonly caused by bacteria or viruses.

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Pneumonia

An infection that inflames the lungs, often caused by bacteria, viruses, or fungi. It can lead to shortness of breath and coughing.

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LD50

The amount of a substance (like bacteria or a toxin) that can kill 50% of a group of test animals.

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Virulence Factors

Features of a microbe that allow it to cause disease by helping it evade the body's defenses.

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Virulence Factor Example

A structure or product made by a microorganism that helps it cause disease.

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Virulence Factor Example (Capsule)

Virulence factors can be structures, like a capsule protecting the microbe from immune cells.

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Virulence Factor Example (Toxin)

Virulence factors can also be products, like toxins that damage the host's cells.

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Coagulase

A protein produced by some bacteria, like Staphylococcus aureus, that helps them form blood clots, which can protect them from the immune system.

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IgA Protease

An enzyme found in some pathogens that breaks down IgA, a type of antibody found in mucous membranes, allowing the pathogen to evade the immune system.

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Staphylococcus aureus

A harmful bacterium that can be found in the nose or on skin and is known to cause infections like skin boils, pneumonia, and food poisoning.

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Secretory IgA

A type of antibody found in mucous membranes that helps protect the body from infections.

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Mucous Surface

The sticky layer that lines the mucous membranes, serving as a barrier against invading pathogens.

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Toxoid

A toxin that has been treated to reduce its toxicity while retaining its ability to stimulate the immune system to produce antibodies.

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Toxoid production

The process of treating a toxin to reduce its toxicity while retaining its ability to stimulate an immune response.

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Antigenicity

The ability of a substance to trigger an immune response, like the production of antibodies.

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Antigen

A substance that triggers an immune response and activates the immune system to produce antibodies.

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Vaccination

The process of introducing a weakened or inactive form of a pathogen into the body to stimulate an immune response and provide immunity against the disease.

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Study Notes

Bacterial Nutrition

  • Heterotrophic bacteria obtain food from other organisms
  • Saprophytic bacteria live freely and obtain nutrients from dead or decaying organic matter (e.g., decomposers in soil). They do not need a live host.
  • Parasitic bacteria obtain nutrients from a living host; this harms the host (e.g., pathogenic bacteria).

Microorganisms as Pathogens

  • A microorganism is a pathogen if it is capable of causing disease.
  • Pathogenicity is the ability of a microorganism to cause disease in a specific host.
  • Pathogens can be infectious or non-infectious

Parasitic Bacteria Classification

  • Pathogenic (Parasites): Bacteria that multiply in host tissue, causing disease
  • Non-Pathogenic (Commensals): Bacteria that live on surfaces of the body without causing disease. Some are beneficial (e.g., producing vitamins B and K) by relation to mutualism.
  • Opportunistic Pathogens: Commensal bacteria that can cause disease under certain conditions (e.g., weakened immune system). Some examples of these conditions are lowered host defense mechanisms such as diabetes, HIV, and chemotherapy.

Infection and Disease Definitions

  • Infection is the process by which a parasite enters a host
  • Disease is damage to host tissue by invasion or toxin production by microorganisms
  • Steps of the Infectious Cycle:
    • Source of infection: Either a case or a carrier
      • Case: Person with symptoms harboring the pathogen
      • Carrier: Person who is healthy and carries the pathogen

Transmission & Carriers

  • Carriers: Appear healthy but carry a pathogenic organism and can transmit it to others
  • Types:
    • Transient: During the incubation period
    • Chronic: (e.g., Hepatitis B or C)
  • Transmission:
    • Contact: Touching, kissing, or sexual intercourse
    • Droplet: Short distance spread by droplets
    • Air-borne: Long distance spread by droplets
    • Vector: Insect bite
    • Vertical: Mother to child in-utero or during childbirth
    • Blood-borne: Blood transfusion or injection

Portal of Entry

  • Most pathogens enter through specific portals:
    • Skin and mucous membranes (abrasions, bites)
    • Gastrointestinal tract
    • Respiratory tract
    • Genito-urinary tract

Multiplication and Tissue Damage

  • Parasites multiply locally or spread through the tissues, blood, or lymphatics to target organs.

Portal of Exit

  • Pathogens exit host in secretions (urine, stools, respiratory/genital discharges, and blood).
  • Disease production relies on interactions of microbial factors and host resistance.

Microbial Factors

  • Pathogenicity: Ability to cause disease

  • Virulence: Severity of the disease produced by the microorganism

  • Virulence Factors: Structures/products that help microorganisms overcome body defenses (e.g., adherence factors, invasion factors, toxin production).

    • Adherence Factors: Help bacteria attach to host cells, starting the disease process.
    • Invasion Factors: Help bacteria spread into tissues.
    • Toxin Production: Substances that harm or damage host cells (Exotoxins and Endotoxins).

Toxins

  • Exotoxins: Proteins secreted by living pathogenic bacteria (often Gram-positive); highly diffusible, act on specific cells
  • Endotoxins: Integral part of Gram-negative bacteria cell wall (lipid A in LPS); not diffusible; released when the bacteria dies, causing generalized effects on the body (weakly diffusible)

Toxoid

  • An inactive toxin, treated with formalin; retains its antigenicity, but not its toxicity, used in vaccines, (e.g., tetanus and diphtheria).

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Description

This quiz explores the different types of bacterial nutrition, focusing on heterotrophic, saprophytic, and parasitic bacteria. It also delves into the classification of microorganisms as pathogens and their roles in disease causation. Test your knowledge on how these microorganisms interact with their hosts.

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