chapter 25

Question 1

What is an infection?

Answer 1

When a microorganism is established and grows in a host, with or without harming the host.

Question 2

What is the difference between infection and disease

Answer 2

Infection is the presence of microorganisms, while disease involves actual tissue damage that impairs host function.

Question 3

What are pathogens?

Answer 3

Microbial parasites that cause disease or tissue damage in a host.

Question 4

What is pathogenicity

Answer 4

The ability of a parasite to damage or harm the host.

Question 5

What is adherence in the context of microbial infection?

Answer 5

It is the enhanced ability of microbes to attach to host tissues.

Question 6

adhesions

Answer 6

glycoproteins or lipoproteins found on the
pathogen’s surface that enable it to bind to host cells

Question 7

Is adherence enough to start disease?

Answer 7

No, adherence is necessary but not sufficient to start disease

Question 8

What are the portals of entry for pathogens?

Answer 8

Mucous membranes, skin surface, and parenteral (e.g., puncture wounds, insect bites, cuts).

Question 9

receptors

Answer 9

coat the pathogen and tissues where the
bacteria or virus binds

Question 10

What is the function of bacterial capsules in microbial adherence?

Answer 10

Capsules are sticky and contain specific receptors to help bacteria attach to host tissues.

Question 11

How do capsules help bacteria evade the immune system?

Answer 11

Capsules protect bacteria from ingestion by white blood cells, aiding in immune evasion.

Question 12

What is an example of a bacterium with an encapsulated strain?

Answer 12

Streptococcus pneumoniae, which has capsules that protect it from immune responses

Question 13

What are fimbriae, pili, and flagella used for in bacteria?

Answer 13

They are used for attachment to host cells.

Question 14

How do pili differ from fimbriae

Answer 14

Pili are longer and fewer in number than fimbriae.

Question 15

What additional function do some pili serve besides attachment?

Answer 15

Some pili are involved in bacterial genetic transfer through conjugation.

Question 16

Can flagella play a role in microbial adherence?

Answer 16

Yes, flagella can also help bacteria adhere to host cells.

Question 17

Colonization

Answer 17

growth of microorganisms after they’ve
gained access to host tissues

Question 18

when does colonization begin

Answer 18

The process begins at birth

Question 19

colonization Typically starts with

Answer 19

mucous membranes, or tightly
packed epithelial cells coated in mucus

Question 20

mucus

Answer 20

a thick liquid secretion of glycoproteins

Question 21

What is dental caries and what causes it?

Answer 21

Dental caries, or cavities, are caused by oral microbial diseases, specifically the growth of bacteria like Streptococcus sobrinus and Streptococcus mutans.

Question 22

What is the role of Streptococcus sobrinus and Streptococcus mutans in dental caries?

Answer 22

These bacteria attach to teeth, reproduce, and form a biofilm called plaque.

Question 23

What is a biofilm in the context of dental caries?

Answer 23

A biofilm is a microbial community that forms on the teeth, contributing to plaque buildup in dental caries.

Question 24

What is infection in the context of microbial diseases?

Answer 24

Infection occurs when a microorganism, not part of the local flora, is established and growing in a host.

Question 25

What is invasion in terms of pathogens?

Answer 25

Invasion is the ability of a pathogen to grow in host tissue at densities that inhibit the host's function.

Question 26

What is bacteremia?

Answer 26

Bacteremia is the presence of bacteria in the bloodstream.

Question 27

What is septicemia?

Answer 27

septicemia is a bloodborne systemic infection that can lead to massive inflammation, septic shock, and death.

Question 28

What is virulence?

Answer 28

Virulence is the relative ability of a pathogen to cause disease.

Question 29

What are virulence factors?

Answer 29

Virulence factors are toxic or destructive substances produced by a pathogen that enhance invasiveness and host damage during infection

Question 30

How can virulence be measured?

Answer 30

Virulence can be estimated by the amount of an agent that kills 50% of the animals in a test group.

Question 31

What does it indicate if a pathogen is highly virulent?

Answer 31

Highly virulent pathogens show little difference in the number of cells required to kill 100% versus 50% of the population

Question 32

What is attenuation in pathogens?

Answer 32

Attenuation is the decrease or loss of virulence in a pathogen.

Question 33

Why are attenuated strains of pathogens valuable in medicine?

Answer 33

Attenuated strains are used in the production of viral vaccines.

Question 34

when pathogens are kept in laboratory cultures rather then isolsated from diseased animal their virulence often

Answer 34

decreases or may be lost

Question 35

What are pathogenicity islands in Salmonella?

Answer 35

Pathogenicity islands are clusters of genes on the chromosome that direct invasion and are considered virulence factors.

Question 36

What is the role of plasmids in bacterial virulence?

Answer 36

Plasmids, particularly resistance plasmids (R plasmids), carry genes that can provide resistance to antibiotics and contribute to virulence.

Question 37

What is an opportunistic infection?

Answer 37

An opportunistic infection is caused by organisms that do not cause disease in healthy hosts but can infect compromised hosts

Question 38

What are nosocomial infections?

Answer 38

Nosocomial infections are healthcare-associated infections, affecting nearly 2 million people each year.

Question 39

How do certain medical procedures or underlying conditions predispose individuals to infections?

Answer 39

Procedures like surgery or conditions such as HIV weaken the immune system, making individuals more susceptible to infections.

Question 40

What is the role of hyaluronidase in virulence?

Answer 40

Hyaluronidase breaks down host tissues, aiding in invasiveness.

Question 41

What is the function of coagulase in pathogenicity?

Answer 41

Coagulase forms clots, which help protect the pathogen from immune response

Question 42

What does streptokinase do in relation to clotting?

Answer 42

Streptokinase breaks down clots, allowing pathogens to spread through tissues

Question 43

What are exotoxins?

Answer 43

Exotoxins are proteins released from the pathogen cell that cause toxicity by inhibiting host cell function or killing host cells.

Question 44

What are the three categories of exotoxins?

Answer 44

The three categories are cytolytic toxins, AB toxins, and superantigen toxins.

Question 45

What does toxicity refer to in the context of pathogens?

Answer 45

Toxicity refers to the ability of an organism to cause disease by producing toxins that damage host cells or inhibit their function.

Question 46

What are AB-type exotoxins?

Answer 46

Toxins with an Active (A) domain and a Binding (B) domain.

Question 47

Name examples of AB-type exotoxins.

Answer 47

Diphtheria, tetanus, botulism, cholera.

Question 48

What does the Binding (B) domain do?

Answer 48

Helps the toxin attach to host cells.

Question 49

What does the Diphtheria Exotoxin do?

Answer 49

Blocks protein synthesis by adding an ADP-ribosyl group to EF-TU.

Question 50

What is the result of ADP-ribosylation in diphtheria exotoxin?

Answer 50

It prevents EF-TU from functioning in translation

Question 51

What do botulinum and tetanus toxins affect?

Answer 51

They affect nervous tissue.

Question 52

What is unique about botulinum toxin?

Answer 52

It's one of the most potent biological toxins known.

Question 53

What type of toxin is tetanus toxin?

Answer 53

Tetanus toxin is an AB protein neurotoxin

Question 54

What do enterotoxins affect?

Answer 54

They affect the small intestine.

Question 55

What do enterotoxins cause in the intestine

Answer 55

They cause massive fluid secretion, leading to vomiting and diarrhea.

Question 56

Which bacterium produces cholera enterotoxin?

Answer 56

vibrio cholerae produces cholera enterotoxin.

Question 57

Vibrio cholerae, the causative agent of the waterborne disease

Answer 57

cholera

Question 58

What do cytolytic exotoxins do?

Answer 58

They degrade cytoplasmic membrane integrity, causing cell lysis and death.

Question 59

What are toxins that lyse red blood cells called?

Answer 59

Hemolysins.

Question 60

What does Staphylococcal toxin do?

Answer 60

It kills nucleated cells and lyses erythrocytes.

Question 61

What do superantigens cause?

Answer 61

They cause an overstimulation of the immune system, potentially leading to shock and death

Question 62

Q: Which bacteria are major producers of superantigens?

Answer 62

Staphylococcus aureus and Streptococcus pyogenes.

Question 63

What can trigger superantigen poisoning?

Answer 63

Food poisoning (especially from S. aureus enterotoxins), toxic shock syndrome, or pyrogenic fever.

Question 64

What are endotoxins?

Answer 64

Endotoxins are toxic lipopolysaccharides found in the cell walls of most gram-negative bacteria

Question 65

Are endotoxins proteins?

Answer 65

No, endotoxins are not proteins; they are structural components of the gram-negative outer membrane.

Question 66

When are endotoxins released in toxic amounts?

Answer 66

Endotoxins are released in toxic amounts when the bacterial cells lyse

Question 67

How do the toxicity levels of endotoxins compare to exotoxins?

Answer 67

Endotoxins are generally less toxic than exotoxins.

Question 68

What is the Limulus amoebocyte lysate (LAL) assay used for?

Answer 68

The LAL assay is used to detect the presence of endotoxins.

Question 69

Why is overharvesting of horseshoe crabs a concern?

Answer 69

Overharvesting is a concern because horseshoe crab blood is used in the LAL assay to detect endotoxins.