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Biology 228: Microbiology > Chapter 15 > Flashcards

Chapter 15 Flashcards

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1
Q

What is infection?

A

When a microorganism enter a host and begins to multiply.

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2
Q

What is disease?

A

It is any deviation from the normal function or structure of the host. Some infections cause disease.

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3
Q

What are pathogens?

A

Microorganisms that can cause disease.

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4
Q

Define signs of a disease.

A

Objective and measured.

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5
Q

Define symptoms of a disease.

A

Subjective and are reported by the patient.

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6
Q

What does asymptomatic or subclinical mean?

A

They do not present any noticeable sign or symptoms.

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7
Q

What is syndrome?

A

A specific group of signs and symptoms characteristic of a particular disease is called a syndrome.

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8
Q

What is a noninfectious disease?

A

Due to genetics and environment.

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9
Q

What is an infectious disease?

A

Due to pathogens.

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10
Q

What is a communicable disease?

A

Transmissible between individuals.

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11
Q

What is a contagious disease?

A

Easily transmissible between individuals.

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12
Q

What are noncommunicable diseases?

A

May be contracted via contact with environmental reservoirs or animals (zoonoses)

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13
Q

What are nosocomial disease?

A

Contracted in hospital settings

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14
Q

What is a iatrogenic disease?

A

The direct result of a medical procedure.

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15
Q

What is acute disease?

A

Short in duration.

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16
Q

What is chronic disease?

A

Lasts for months or years.

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17
Q

What is latent disease?

A

Last for years with extended dormant periods.

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18
Q

What are Koch’s Postulates?

A

Used to determine whether a particular microorganism is a pathogen.

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19
Q

What is molecular Koch’s postulates?

A

Used to determine what genes contribute to a pathogen’s ability to cause disease.

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20
Q

What are the four determinants of Koch’s Postulates?

A
  1. The suspected pathogen must be found in every case of disease and not be found in healthy individuals.
  2. The suspected pathogen can be isolated and grown in pure culture.
  3. A healthy test subject infected with the suspected pathogen must develop the same signs and symptoms of disease as seen in postulate 1.
  4. The pathogen must be re-isolated from the new host and must be identical to the pathogen from postulate 2.
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21
Q

What is the application to EHEC?
The phenotype (sign or symptom of the disease) should be associated only with pathogenic strains of a species.

A

EHEC causes intestinal inflammation and diarrhea, whereas nonpathogenic strains of E. coli do not.

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22
Q

What is the application to EHEC?
Inactivation of the suspected gene(s) associated with pathogenicity should result in a measurable loss of pathogenicity.

A

One of the genes in EHEC encodes for Shiga toxin, a bacterial toxin (poison) that inhibits protein synthesis. Inactivating this gene reduces the bacteria’s ability to cause disease.

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23
Q

What is the application to EHEC?
Reversion of the inactive gene should restore the disease phenotype.

A

By adding the gene that encodes the toxin back into the genome (e.g., with a phage or plasmid), EHEC’s ability to cause disease is restored.

24
Q

What is pathogenicity?

A

The ability of a microbial agent to cause disease.

25
Q

What is virulence?

A

The degree to which a pathogen can cause disease.
- Can be quantified by calculating either the ID50 or LD50 of a pathogen on a given population.

26
Q

What are primary pathogens?

A

Are capable of causing pathological changes associated with disease in a healthy individual.

27
Q

What are opportunistic pathogens?

A

Can only cause disease when the individual is compromised by a break in protective barriers or immunosuppression.

28
Q

What can infections and diseases be caused by?

A

Pathogens in the environment or microbes in an individual’s resident microbiota.

29
Q

When can a secondary infection occur?

A

After the host’s defenses or normal microbiota are compromised by a primary infection or antibiotic treatment.

30
Q

What are the 5 stages of pathogenesis?

A
  • Exposure
  • Adhesion
  • Invasion
  • Infection
  • Transmission
31
Q

What is exposure?

A

An encounter with a potential pathogen able to gain access into host tissue.
Mucosal surfaces are the most important portals of entry for microbes.

32
Q

What is a parental route?

A

A breach in the protective barriers

33
Q

What are the diseases capable of crossing the placental barrier?

A

T - Toxoplasmosis
O - Syphilis, Chickenpox, Hepatitis B, HIV, Fifth disease (erythema infectiosum)
R - Rubella (German measles)
C - Cytomegalovirus
H - Herpes

34
Q

What is adhesion?

A

The capability of pathogenic microbes to attach to the cells of the body using adhesion factors.

35
Q

Where are adhesins found?

A

On the surface of certain pathogens and bind to specific receptors (glycoproteins) on host cells (fimbriae and flagella of bacteria, the cilia of protozoa, and the capsids or membranes of viruses).

36
Q

What is invasion?

A

It involves the dissemination of a pathogen throughout local tissues or the body.
Pathogens may produce exoenzymes or toxins, which serve as virulence factors that allow them to colonize and damage host tissues as they spread deeper into the body.

37
Q

What is infection?

A

Infections can be classified as local, focal, or systemic depending on the extent to which the pathogen spreads in the body.

38
Q

What is transmission?

A

For a pathogen to persist, it must put itself in a position to be transmitted to a new host, leaving the infected host through a portal of exit.

39
Q

What are virulence factors?

A

Virulence factors contribute to a pathogen’s ability to cause disease.

40
Q

What are exoenzymes?

A

Exoenzymes and toxins allow pathogens to invade host tissue and cause tissue damage. Exoenzymes are classified according to the macromolecule they target.

41
Q

What is the function of the glycohydrolases?

A

Degrades hyaluronic acid that cements cells together to promote spreading through tissues.
Ex. Hyaluronidase S in Staphylococcus aureus.

42
Q

What is the function of nucleases?

A

Degrade DNA released by dying cells (bacteria and host cells) that can trap the bacteria, thus promoting spread.
Ex. DNAse produced by S. aureus.

43
Q

What is the function of phospholipases?

A

Degrades phospholipid bilayer of host cells, causing cellular lysis, and degrade membrane of phagosomes to enable escape into the cytoplasm.
Ex. Phospholipase C of Bacillus anthracis.

44
Q

What is the function of proteases?

A

Degrades collagen in connective tissue to promote spread.
Ex. Collagenase in Clostridium perfringens.

45
Q

What is an endotoxin?

A

The lipopolysaccharide (LPS) found on the outer membrane of gram-negative bacteria.

46
Q

When do gram negative bacterial pathogens release endotoxin?

A

Either when the cell dies or when the bacterium undergoes binary fission.
Lipid A triggers the immune system’s inflammatory response.

47
Q

How can toxins be classified?

A

They can be categorized as endotoxins or exotoxins.

48
Q

How are exotoxins classified?

A

Based on their mechanism of action.

49
Q

CHART IN SLDES CHAPTER 15 SLIDE 34

A
50
Q

What are some examples of categories of exotoxins?

A
  • Intracellular targeting toxins
  • Membrane disrupting toxins
  • Superantigens
51
Q

How could bacterial pathogens evade the host immune response?

A

By producing capsules to avoid phagocytosis, surviving the intracellular environment of phagocytes, degrading antibodies, or through antigenic variation.

52
Q

How do viral pathogens avoid immune defenses?

A

Use adhesins for initiating infections and antigenic variation to avoid immune defenses.

53
Q

What do influenza viruses use antigenic drift and antigenic shift to avoid?

A

Being recognized by the immune system.

54
Q

How are fungal and parasitic pathogens similar to bacterial pathogens?

A

Use pathogenic mechanisms and virulence factors that are similar to those of bacterial pathogens.

55
Q

How do fungi initiate infections?

A

Through the interaction of adhesins with receptors on host cells. Some fungi produce toxins and exoenzymes involved in disease production and capsules that provide protection of phagocytosis.

56
Q

How do protozoa adhere to target cells?

A

Through complex mechanisms and can cause cellular damage through release of cytopathic substances. Some protozoa avoid the immune system through antigenic variation and production of capsules.

57
Q

How do helminthic worms avoid the immune system?

A

By coating their exteriors with glycan molecules that make them look like host cells or by suppressing the immune system.

Biology 228: Microbiology (20 decks)

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