Bacterial Nutrition and Host-Parasite Relationship
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Questions and Answers

What condition can occur if bacteria reach the urinary system?

  • Urinary tract infection (UTI) (correct)
  • Meningitis
  • Pneumonia
  • Gastroenteritis

Which bacteria may cause endocarditis after dental procedures?

  • Pseudomonas aeruginosa
  • Staphylococcus aureus
  • Escherichia coli
  • Streptococcus Viridans (correct)

What is E. Coli primarily known for?

  • Causing foodborne illness only
  • Having no significant role in the human body
  • Being a normal inhabitant of the intestine (correct)
  • Living exclusively in water environments

In what context is E. Coli mentioned?

<p>As a beneficial bacterium found in the intestine (A)</p> Signup and view all the answers

What prior condition increases the risk of endocarditis following tooth extraction?

<p>Predisposing heart lesion (B)</p> Signup and view all the answers

What is the primary way for Streptococcus Viridans to enter the bloodstream?

<p>Following a tooth extraction (B)</p> Signup and view all the answers

What factor has changed in relation to the natural habitat of organisms like E. Coli?

<p>A shift in the typical environment of organisms (C)</p> Signup and view all the answers

Which of the following infections is not related to Streptococcus Viridans?

<p>Urinary tract infection (UTI) (A)</p> Signup and view all the answers

Which statement about E. Coli is incorrect?

<p>E. Coli only exists in contaminated food. (A)</p> Signup and view all the answers

How does the change in natural habitat affect E. Coli's role?

<p>It enhances its ability to cause infections. (C)</p> Signup and view all the answers

What does pathogenicity refer to?

<p>The ability of an organism to cause disease (B)</p> Signup and view all the answers

What can occur at the portal of entry of a parasite within a susceptible host?

<p>The parasite may multiply locally. (C)</p> Signup and view all the answers

How is pathogenicity primarily characterized?

<p>Qualitative assessment of disease causation (B)</p> Signup and view all the answers

Which aspect does pathogenicity NOT include?

<p>The ability to reproduce in multiple environments (A)</p> Signup and view all the answers

How can the parasite spread within a susceptible host?

<p>Through tissues, blood, or lymphatics. (D)</p> Signup and view all the answers

What is a possible consequence of parasite multiplication within the host?

<p>Tissue damage in the target organ. (C)</p> Signup and view all the answers

Which of the following best describes the nature of pathogenicity?

<p>It is a qualitative measure of disease capability (A)</p> Signup and view all the answers

What factor is essential to consider when discussing pathogenicity?

<p>The interaction with host immune responses (D)</p> Signup and view all the answers

When a parasite invades the body, what may be a first point of impact?

<p>The portal of entry. (D)</p> Signup and view all the answers

Where might a parasite spread after entering the host?

<p>To the circulatory system. (A)</p> Signup and view all the answers

What is the primary function of collagenase?

<p>To break down collagen fibers and promote infection spread (B)</p> Signup and view all the answers

What substance does hyaluronidase primarily act upon?

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

What is the role of hyaluronic acid within connective tissue?

<p>To act as a lubricant and filler (D)</p> Signup and view all the answers

Collagenase is primarily associated with which process?

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

Which of the following statements about hyaluronidase is true?

<p>It decreases the viscosity of connective tissues. (D)</p> Signup and view all the answers

Where are the genes controlling protein production located?

<p>On a plasmid or bacteriophage (C)</p> Signup and view all the answers

Which of the following is true about the antigenicity of Lipid A?

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

What is a characteristic symptom of proteins acting on target cells?

<p>Specific action on target cells (C)</p> Signup and view all the answers

Which type of structures does Lipopolysaccharide (LPS) typically consist of?

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

What is the nature of the genes controlling lipid A production?

<p>Carried mainly on plasmids (C)</p> Signup and view all the answers

Flashcards

Parasite Multiplication

The increase in the number of parasites within a host's body.

Portal of Entry

The point where a parasite enters a host's body.

Parasite Spread

Parasites spreading throughout the body via blood or lymphatic system.

Target Organ

The specific organ or tissue a parasite targets.

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Tissue Damage

Damage caused by the growth and activity of parasites within the host's body.

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Natural Habitat

The environment where an organism naturally lives and thrives.

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E. coli

A type of bacteria that is commonly found in the intestines of humans and animals.

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Change in Natural Habitat

A change in the environment where an organism lives.

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Normal Inhabitant

An organism that normally resides in a specific environment.

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Impact of Habitat Change

Changes to an organism's natural habitat can affect its survival and well-being.

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Urinary Tract Infection (UTI)

A type of infection affecting the urinary tract, typically caused by bacteria entering the system.

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Streptococcus Viridans

Commonly found in the mouth, these bacteria can cause heart infections if they enter the bloodstream, especially for those with pre-existing heart conditions.

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Bacteremia

The presence of bacteria in the bloodstream.

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Endocarditis

Inflammation of the inner lining of the heart, often caused by bacteria.

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Predisposing Heart Lesion

A pre-existing health condition that makes a person more susceptible to a disease.

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Pathogenicity

The ability of a microorganism (like bacteria or a virus) to cause disease.

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Qualitative Pathogenicity

Pathogenicity refers to the qualitative aspect of a microbe's ability to cause disease. It simply tells us whether the microbe can cause disease or not.

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Pathogenicity vs Virulence

Pathogenicity is about whether a microbe can cause disease, while virulence is about how severe the disease is.

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Virulence

Virulence is the degree or intensity of disease caused by a microbe. It's a quantitative measure.

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Virulence Factors

Virulen factors are specific components or mechanisms used by microbes to cause disease. They contribute to the severity of the disease.

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Collagenase

An enzyme that breaks down collagen fibers, a major component of connective tissue. This allows infections to spread more easily.

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Hyaluronidase

An enzyme that breaks down hyaluronic acid, a sticky substance found in connective tissue. This also helps infection spread.

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Genes controlling toxin production

Found on plasmids or bacteriophages, these genes are responsible for the production of toxins by bacteria.

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Lipid A

A component of the outer membrane of Gram-negative bacteria, Lipid A is the toxic part of lipopolysaccharide (LPS).

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Toxins' actions on target cells

Toxins produced by bacteria generally exert specific effects on target cells, often causing cell damage or dysfunction.

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Chemical composition of toxins

The chemical composition of a toxin can vary, affecting how it interacts with and harms the body.

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Antigenicity of toxins

Toxins are highly antigenic, meaning they trigger a strong immune response with high antibody production.

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Study Notes

Bacterial Nutrition

  • Bacteria obtain nutrients from various sources
  • Heterotrophic bacteria rely on other organisms for food
    • Saprophytic bacteria consume dead or decaying organic matter
    • Parasitic bacteria obtain nutrients from a living host, potentially causing harm
  • Microorganisms are pathogenic if they have the ability to cause disease
    • Pathogenicity details the capability of causing disease in a particular host

Host-Parasite Relationship

  • Bacteria can be pathogenic (causing disease) or non-pathogenic (commensal)

    • Pathogenic bacteria: multiply in the host's tissues
    • Non-pathogenic bacteria: reside on surfaces without harming the host
      • Can even be beneficial, producing vitamins like B and K or competing with pathogens

  • Commensal bacteria can be beneficial to the host, competing against pathogens through:

    • Covering binding sites, preventing pathogen attachment and colonization
    • Competing for nutrients, inhibiting pathogen growth
    • Producing toxic substances, such as lactic acid in the vagina
    • Inhibiting the growth of pathogenic bacteria and fungus

  • Opportunistic pathogens are commensal bacteria that can cause disease under specific conditions

    • Examples: lowered host defense mechanisms (diabetes, HIV, chemotherapy)

  • Infection involves the parasite entering into a relationship with the host, through entry and multiplication

  • Disease defined as the damage of the host tissue due to invasion or toxin production

    • Infection steps called the Infectious Cycle
      • Source is either a case or a carrier (individuals that harbor, and transmit the microorganism, exhibiting clinical signs and symptoms)

Carriers

  • Carriers are apparently healthy individuals who carry pathogenic organisms.
  • Types of carriers:
    • Transient carriers: during the incubation period
    • Chronic carriers: long term such as with Hepatitis B or C
  • Carriers are more dangerous than cases for transmission, as they are not typically known to the public, difficult to detect, and not restricted to bed

Modes of Transmission

  • Contact transmission (Skin-to-skin contact)
    • Includes sexual intercourse, touching, kissing
  • Droplet infection (Microbes spread in droplets)
    • Short distances, less than a meter e.g. coughing, sneezing
  • Airborne transmission
    • Longer distances than droplets, over a meter e.g. Tuberculosis, Measles.

Portal of Entry and Multiplication

  • Specific portals, such as skin, mucous membranes, gastrointestinal or respiratory tracts
  • Multiplication within host tissue; spreads locally

Portal of Exit

  • Secretions like urine, stool, respiratory or genital discharges, blood

Factors Governing Disease Production

  • Most infections are either abortive, silent, or subclinical
  • Outcome depends on interaction between microbial and host factors

Microbial Factors

  • Pathogenicity: Ability to cause disease
  • Virulence: Severity of disease a microorganism can cause
    • Determined by production, amount, and potency of toxin
  • Virulence Factors
    • Adherence factors help microorganisms attach to host cells, starting the disease process
    • Invasion factors enable the microorganisms to invade host tissues
  • Extracellular Enzymes that promote microbial spread and invade tissues
    • Collagenase, Hyaluronidase, Lecithinase, IgA Protease, Coagulase; Fibrinolysin, DNase

Toxin Production

  • Bacteria produce toxins with harmful effects on tissue cells
  • Classified into exotoxins and endotoxins
    • Exotoxins: proteins, diffuse freely, highly antigenic, produced by living bacteria
    • Endotoxins: part of the cell wall, less antigenic, produced when bacteria dies
  • Toxoids are inactivated toxins used in vaccines, preserving antigenicity without toxicity.

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Medical Microbiology EDPT 211 Past Paper PDF

Description

Explore the fascinating world of bacteria and their nutritional strategies. This quiz delves into the differences between pathogenic and non-pathogenic bacteria, their host relationships, and the significance of commensal bacteria in preventing diseases. Test your knowledge on how these microorganisms impact human health.

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