Microbiology Chapter 15 Flashcards

Questions and Answers

What is the term meaning the ability to cause disease?

Infectious dose

Toxemia

Pathogenicity (correct)

Virulence

What is the term for the measurement of pathogenicity?

Toxemia

Virulence (correct)

Infectious dose

Pathogenicity

What are the steps of microbial mechanisms?

Portal of entry, adherence, penetration into the host cell, evasion, damage to host tissue.

What are the three ways microbes get inside host?

Mucous membranes, skin, parenteral route. Signup and view all the answers

What is the easiest and most often used mucous membrane for portal of entry?

Respiratory tract. Signup and view all the answers

What is the mucous membrane portal of entry where most microbes are killed?

Gastrointestinal tract. Signup and view all the answers

What are some examples of the microbes that enter through the respiratory tract?

Pneumonia, tuberculosis, influenza, measles, smallpox. Signup and view all the answers

What are some examples of the microbes that enter through the GI?

Typhoid fever, poliomyelitis, shigellosis. Signup and view all the answers

What is the portal entry for STDs?

Genitourinary tract. Signup and view all the answers

How do microbes enter through the GU?

Through unbroken mucous membranes, cuts, or abrasions. Signup and view all the answers

What are some examples of the viruses that enter through the GU?

Genital warts, herpes, HIV. Signup and view all the answers

When microbes enter through hair follicles or sweat glands, what tissue are they using?

Skin. Signup and view all the answers

What portal of entry is used when microbes enter through punctures, injections, or bites?

Parenteral route. Signup and view all the answers

What are some examples of diseases that can cause infection using a specific mode of entry?

Salmonella typhimurium (ingested), Streptococcus pneumoniae (inhaled), Yersinia pestis (bubonic plague). Signup and view all the answers

If the infectious dose for a sample population is 50%, how would you express this measurement of virulence?

ID50. Signup and view all the answers

What does a low number in infectious dose or lethal dose measurements mean in regards to the virulence?

The lower the number, the higher the virulence. Signup and view all the answers

If the lethal dose for a sample population is 50%, how would you express this measurement?

LD50. Signup and view all the answers

What is the difference between lethal dose measurements and infectious dose measurements?

Lethal kills and infectious makes you sick. Signup and view all the answers

In adherence, what helps the microbe adhere to the host?

Surface molecules called adhesins or ligands. Signup and view all the answers

What is the term for communities of microbes and their products that attach to surfaces?

Biofilm. Signup and view all the answers

Biofilm is what percentage of all bacterial infection?

65%. Signup and view all the answers

What must the microbe do to infect a host cell after it attaches to it?

Penetrate the host cell. Signup and view all the answers

When the microbe attaches to the host cell, what changes occur in the host cell?

In the plasma membrane. Signup and view all the answers

What are some of the ways that microbes employ evasion?

Use of capsule, components of the cell wall (M protein), enzymes (such as coagulase, kinases, hyaluronidase, collagenase, IgA proteases), and antigenic variation. Signup and view all the answers

What component of a cell wall does a microbe use in evasion?

M protein. Signup and view all the answers

What enzyme clots fibrin?

Coagulase. Signup and view all the answers

How does the enzyme coagulase help the microbe in evasion?

It shields the microbe from white blood cells. Signup and view all the answers

What enzyme breaks down fibrin?

Kinase. Signup and view all the answers

How does the enzyme kinase help the microbe in evasion?

It breaks away from blood clots when immune cells try to isolate the microbe. Signup and view all the answers

What enzyme breaks down hyaluronic acid?

Hyaluronidase. Signup and view all the answers

How does the enzyme hyaluronidase help the microbe in evasion?

It acts as a spreading factor to move through cells. Signup and view all the answers

What enzyme breaks down collagen?

Collagenase. Signup and view all the answers

What enzyme destroys IgA antibodies?

IgA proteases. Signup and view all the answers

How does the microbe use antigenic variation?

It alters surface proteins so that it cannot be fought with existing antibodies. Signup and view all the answers

How does the microbe damage the host tissues?

By using host nutrients. Signup and view all the answers

What are the steps that the siderophores go through to get the nutrients (iron) and bring it back to the bacterium?

Produce siderophores, siderophore binds to iron, siderophore binds to bacteria, bacterium takes siderophore inside. Signup and view all the answers

What is the protein that binds iron stronger than hemoglobin?

Siderophores. Signup and view all the answers

What is the direct damage to host tissues?

Multiplying until cell ruptures, depriving host cell of needed nutrients, producing toxic waste products, and toxins. Signup and view all the answers

What is the poisonous substance that is mostly protein enzymes?

Toxin. Signup and view all the answers

What is the measure of the virulence of the toxin?

Toxigenicity. Signup and view all the answers

What is the term that refers to a toxin in the blood?

Toxemia. Signup and view all the answers

What are the two types of toxins?

Exotoxins and endotoxins. Signup and view all the answers

What is the product that is produced by a bacterium, secreted by proteins, and is the most lethal substance known?

Exotoxins. Signup and view all the answers

What are the antibodies produced by the body that can bind to the exotoxin?

Antitoxins. Signup and view all the answers

What is the altered toxin used to stimulate the immune system?

Toxoid. Signup and view all the answers

What are some examples of a toxoid?

Diphtheria and tetanus. Signup and view all the answers

What are some examples of diseases caused by bacterial exotoxins?

Botulism and staphylococcus food poisoning. Signup and view all the answers

In A-B toxins, the A is what part of the exotoxin?

Active. Signup and view all the answers

In A-B toxins, the B is what part of the exotoxin?

Binding. Signup and view all the answers

What kind of toxin inhibits protein synthesis and kills the cell?

A-B toxins. Signup and view all the answers

What exotoxin causes lysis in the host cell plasma membrane?

Membrane-disrupting toxins. Signup and view all the answers

What exotoxin makes proteins in the plasma membrane and disrupts the phospholipid layer?

Membrane-disrupting toxins. Signup and view all the answers

What are some examples of membrane-disrupting toxins?

Leukocidins and hemolysins. Signup and view all the answers

The membrane-disrupting toxin leukocidins is a toxin that kills what?

WBC. Signup and view all the answers

The membrane-disrupting toxin hemolysins is a toxin that kills what?

RBC. Signup and view all the answers

What is the term for an intense immune response or a super immune response?

Superantigens. Signup and view all the answers

What product produced by a bacterium is part of the cell wall and is only released when the cell wall is damaged?

Endotoxin. Signup and view all the answers

What response is present when a Gram-negative cell is ingested by a macrophage?

Pyrogenic response. Signup and view all the answers

What condition is due to a loss of blood pressure due to an endotoxin?

Septic shock. Signup and view all the answers

What condition results when tumor necrosis factor (TNF-a) makes capillaries permeable?

Septic shock. Signup and view all the answers

Septic shock can cause large amounts of fluids to be lost and may even cause what?

Death. Signup and view all the answers

Which measure (LD or ID) is used to express virulence of pathogens or toxins?

LD. Signup and view all the answers

In a biofilm, what is the first layer?

Bacteria. Signup and view all the answers

Dental plaque, algae on a pool, and soap scum are all examples of what?

Biofilm. Signup and view all the answers

How does the enzyme collagenase help with evasion?

It acts as a spreading factor that helps move through collagen. Signup and view all the answers

What exotoxins attack nerve cells?

Neurotoxin. Signup and view all the answers

What exotoxin attacks GI tract cells?

Enterotoxin. Signup and view all the answers

What exotoxin attacks heart cells?

Cardiotoxin. Signup and view all the answers

Study Notes

Pathogenicity and Virulence

Pathogenicity is the ability of an organism to cause disease.
Virulence measures the degree or intensity of pathogenicity.

Microbial Mechanisms

Infection begins with a portal of entry: mucous membranes, skin, and parenteral routes.
Key steps for microbes: adherence to host, penetration into host cells, evasion of immune responses, and damage to host tissues.

Portals of Entry

Respiratory tract is the most common mucous membrane portal for pathogens.
Gastrointestinal tract serves as a portal where many microbes are killed by stomach acid and enzymes, but some can survive and disperse through feces.
Genitourinary tract is a primary entry point for sexually transmitted diseases, with invaders entering via unbroken mucous membranes or through cuts.

Microbial Examples

Common microbes entering via respiratory tract include pneumonia, tuberculosis, influenza, measles, and smallpox.
Examples entering gastrointestinal tract include typhoid fever, poliomyelitis, and shigellosis.
Notable examples of GU viruses are genital warts, herpes, and HIV.

Evasion Strategies

Microbes employ various methods to evade host defenses including capsule use, cell wall components, and enzymatic action.
Enzymes like coagulase help form fibrin clots, shielding microbes from white blood cells (WBC).
Kinases break down fibrin, allowing microbes to escape immune isolation.
Hyaluronidase facilitates movement through tissues by breaking down connective tissue.

Damage to Host Tissues

Damage occurs through several mechanisms: cellular lysis, nutrient depletion, toxic waste accumulation, and toxin production.
Siderophores are proteins that bind iron more tightly than hemoglobin, enabling bacteria to acquire essential nutrients.

Toxin Classification

Toxins are poisonous substances, primarily protein enzymes, classified into exotoxins and endotoxins.
Exotoxins are secreted proteins that can diffuse into the bloodstream and typically show high lethality.
Antitoxins are antibodies formed by the body to neutralize exotoxins.

Special Types of Toxins

A-B toxins inhibit protein synthesis; 'A' is the active component while 'B' binds to host cells.
Membrane-disrupting toxins can lyse host cells, with leukocidins targeting WBCs and hemolysins affecting RBCs.
Superantigens provoke intense immune responses.

Endotoxins

Endotoxins are components of the Gram-negative bacterial cell wall, specifically lipopolysaccharides.
They are released when bacterial cells die or when their wall is damaged, triggering inflammatory responses like fever and septic shock.

Septic Shock

Occurs when endotoxins cause significant drops in blood pressure, potentially leading to death.
TNF-a released by macrophages can increase capillary permeability, contributing to fluid loss and shock.

Biofilms

Biofilms consist of communities of microbes that adhere to surfaces, significant in infections and resistance to treatment.
The first layer in a biofilm is typically made up of bacteria, contributing to complex structures like dental plaque.

Additional Exotoxin Types

Neurotoxins target nerve cells, while enterotoxins affect gastrointestinal cells, and cardiotoxins impact heart cells.
Examples of diseases caused by exotoxins include botulism and staphylococcus food poisoning.

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Test your knowledge with these flashcards focusing on Chapter 15 of Microbiology. This chapter covers key terms related to pathogenicity, virulence, and microbial mechanisms. Perfect for students wanting to reinforce their understanding of how microbes cause disease.