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Micro > Microbial Pathogenicity > Flashcards

Microbial Pathogenicity Flashcards

1
Q

What is a pathogen?

A

a microbe that causes a disease

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2
Q

What is a sign?

A

a measurable indicator of a disease that can be observed

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3
Q

What is a symptom?

A

an experience of a disease that a patient can feel, it cannot be objectively measured

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4
Q

What does asymptomatic/subclinical mean?

A

the disease does not show any noticeable symptoms or signs

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5
Q

What does infectious mean?

A

any type of disease that is caused by a pathogen

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6
Q

What does communicable/contagious mean?

A

An infectious disease that can be spread directly or indirectly from one person to another. Contagious diseases are more easily spread from person to person.

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7
Q

What does iatrogenic mean?

A

Transmission of a disease caused by a medical procedure.

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8
Q

What does nosocomial mean?

A

diseases that are obtained in hospital settings

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9
Q

What does zoonotic mean?

A

diseases that are transmitted from animals to humans

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10
Q

What are the five stages of disease?

A
  • incubation period
  • prodromal period
  • period of illness
  • period of decline
  • period of convalescence
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11
Q

What is the incubation period?

A

the time when the pathogen first enters the host. It is adjusting and becoming established. Since the pathogens are just starting to multiply, there are no symptoms or signs of the disease in this period. This period can vary in length depending on the pathogen. It can last from a day to months or years (like lag phase)

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12
Q

What is the prodromal period?

A

the pathogen continues to multiply. The host starts to exhibit some of the general signs and symptoms of a disease.

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13
Q

What is the period of illness?

A

the signs and symptoms become more noticeable and increase in severity. (like log phase)

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14
Q

What is the period of decline?

A

the number of pathogens starts to decrease. The signs and symptoms of the disease also start to decline (like death phase)

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15
Q

What is the period of convalescence?

A

the host returns to normal functions. They feel much better, but they are still not 100% healthy. This phase varies in duration depending on the health status of the patient.

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16
Q

What is an acute disease?

A

occurs over a short period of time. From days to weeks

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17
Q

What is a chronic disease?

A

pathological changes take longer. It can last from months to years.

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18
Q

What is a latent disease?

A

an acute disease goes into a latent phase. It becomes dormant for an extended period of time and can appear later in life.

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19
Q

How are molecular Koch’s postulates different from Koch’s postulates?

A

Koch’s postulates are used to link a pathogen to a disease. There are limitations to these postulates. In molecular Koch’s postulates, the ability to isolate a pathogen is not tested. Instead, it focuses on the ability to identify a gene that could possibly cause the organism to be pathogenic. It looks at why certain strains are pathogenic and why others are not. It links the genetic differences between strains to their pathogenicity.

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20
Q

What is pathogenicity?

A

the ability of a microbe to cause a disease

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21
Q

What is virulence?

A

the measure of the ability of a microbe to cause disease, can range from not harmful to very harmful

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22
Q

What is ID50?

A

Median infectious dose (ID50) is the number of pathogen cells or virions needed to infect 50% of animals in the trial.

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23
Q

What is LD50?

A

Median lethal dose (LD50) is the number of pathogenic cells or virions needed to kill 50% of infected animals

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24
Q

What does a low ID50 mean?

A

A low number of ID50 signifies that it is very easy to cause an active infection in 50% of inoculated animals.

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25
Q

What does a low LD50 mean?

A

A low number in LD50 signifies that a low number of virions are needed to kill 50% of infected animals.

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26
Q

What are the locations in the human body where normal flora/normal microbiota are present?

A

The normal flora are present on the surface tissues. For example, the skin and mucous membranes. Tissues that come in contact with the external environmental

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27
Q

Where is the normal flora absent?

A

The normal flora are absent in internal tissues such as the blood or brain. These tissues are free of microbes.

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28
Q

What are some examples of bacteria and fungi that are normal flora/microbiota?

A

Examples of bacteria in the normal flora are E.coli, micrococcus, bacteriodes, neisseria sp. An example of fungi in the normal flora is Candida albicans.

29
Q

What are primary pathogens?

A

Regardless of a host’s immune system or microbiota, a primary pathogen can cause disease in the host.

30
Q

What are opportunisitic pathogens?

A

opportunistic pathogen can only cause disease in situations that cause the host’s defenses to become compromised.

31
Q

What are 3 ways that normal flora (normal microbiota) can become opportunistic pathogens?

A

1) The first way is when a microbe grows in an environment and gets inserted into the body. For example, a microbe that grows in biofilms that forms on an implant gets inserted into the body. This causes serious infections.
2) The second way is when a microbe that harmlessly inhabits one location in the body ends up in a different system of the body where they can be pathogenic.
3) The third way is when a shift in the environment of the body causes the overgrowth of a certain microbe.

32
Q

What are portals of entry?

A

A portal of entry is a site on the body where a pathogen can get into host tissue. These are generally areas where host cells are in contact with the external environment. Some examples of portals of entry are the eye, nose, mouth, ear, broken skin, needles, insect bites, placenta, and vagina.

33
Q

What are portals of exit?

A

A portal of exit is a location where a pathogen leaves the infected host. Common portals of exit are the eye, nose, mammary glands, placenta, mouth, ear, needle, broken skin, insect bites, urethra, anus, skin, and vagina.

34
Q

Do portals of entry and exit need to be the same for a single disease?

A

Portals of entry and exit do not have to be the same for a single disease.

35
Q

What are TORCH infections?

A

TORCH infections are caused by pathogens that can cross the placental barrier. These pathogens infect the fetus. TORCH stands for toxoplasmosis, other (syphilis, chickenpox, HIV, hepatitis B), rubella, cytomegalovirus, and herpes

36
Q

What other pathogens can cross the placental barrier?

A

Other pathogens that can do this are Listeria monocytogenes and Mycobacterium tuberculosis.

37
Q

What are the adhesion factors?

A
  • adhesin
  • ligand
  • fimbriae/pili (type 1 and type IV)
  • glycocalyx/capsule
  • suction discs
38
Q

What does adhesin do?

A

They bind to specific surface receptors on host cells.

39
Q

What does a ligand do?

A

binds to a specific receptor on the host cell

40
Q

What do fimbriae/pili do?

A

they are able to stick to and attach to host cells, they act as adhesions for specific adherence

41
Q

What to type I fimbriae do?

A

Fimbriae of ETEC cells allow them to attach and bind to intestinal epithelial cells. Specifically, they attach to mannose glycans on the intestinal epithelial cells.

42
Q

What do type IV pili do?

A

Pili that allow a bacterium to bind to urethral epithelial cells.

43
Q

What does the glycocalyx/capsule do?

A

The high sugar and protein content of the glycocalyx allows certain pathogens to attach to cells.

44
Q

What do suction disks do?

A

They are a structure that allows for the attachment to a host.

45
Q

What do biofilms do?

A

They act as adhesion factors. A biofilm is a community of bacteria that makes extrapolymeric substance (EPS). The EPS is what allows the attachment of biofilms to surfaces.

46
Q

What are examples of biofilms?

A

Pseudomonas aeruginosa is an example of a microbe that can produce a biofilm.

47
Q

What are the exoenzymes/invasins?

A
  • hyaluronidase
  • DNase
  • phospholipases
  • collagenase
48
Q

What does hyaluronidase do?

A

Degrades hyaluronic acid that cements adjacent cells together. This allows the pathogen to pass through and spread through tissues.

49
Q

What does DNase do?

A

Degrades extracellular DNA released by cells that are dying. This helps trap the bacteria. It allows the pathogens to escape and spread.

50
Q

What do phospholipases do?

A

Degrades/hydrolyzes the host cell’s phospholipid bilayer causing it to lyse. It also degrades the membrane of phagosomes. This allows pathogens to escape into the cytoplasm.

51
Q

What does collagenase do?

A

Degrades and breaks down collagen in connective tissue. This allows the pathogen to spread through tissues.

52
Q

What are the toxins?

A
  • endotoxins
  • exotoxins
  • superantigens
53
Q

What do endotoxins do?

A

LPS of outer membrane of gram-negative bacteria. It causes general symptoms of fever and inflammation in the host. Lipid A is what gives the LPS its toxic properties.

54
Q

What do exotoxins do?

A

Specific in their action. Targets specific receptors on specific cells. It damages the cells through a unique molecular mechanism.

55
Q

What do superantigens do?

A

Exotoxins that trigger excessive activation of immune cells to release cytokines. The production of cytokines causes a strong immune and inflammatory response. This response can cause life-threatening shock, inflammation, and fever.

56
Q

What are the immune system evasion factors?

A
  • capsules
  • M protein
  • proteases
  • streptokinase/staphylokinase
  • coagulase
  • antigenic variation
57
Q

What do capsules do?

A

Used in adhesion but also help in immune evasion. It prevents phagocytes from ingesting the pathogen. It also makes the pathogen larger to make it difficult for them to be engulfed.

58
Q

What does M protein do?

A

It alters the surface of streptococcus. It also inhibits phagocytosis by blocking the binding of complement molecules.

59
Q

What do proteases do?

A

Protects pathogens against phagocytosis by attacking and digesting antibodies.

60
Q

What does streptokinase/staphylokinase do?

A

Kinases assist in the escape of pathogens trapped in a clot by digesting it. It stimulates the digestion of clots to help a pathogen spread.

61
Q

What does coagulase do?

A

Forms a blood clot around the pathogen to evade the immune system. The clot that forms coats the bacteria protects it from being exposed to phagocytic immune cells in the bloodstream.

62
Q

What is antigenic variation?

A

It alters surface proteins on the pathogen so they cannot be recognized by the immune system of the host cell anymore.

63
Q

What are A-B toxins?

A

1) A subunit and B subunit bind
2) Both enter the cell via receptor-mediated endocytosis
3) A subunit goes off and shuts down something

64
Q

What do the botulinum and tetanus toxins target?

A

the neuromuscular junction

65
Q

What does botulinum toxin do?

A
  • Blocks the release of acetylcholine
  • No contraction of muscle cell
  • Prevents contraction of the muscle cell
  • Called flaccid paralysis
66
Q

What does tetanus toxin do?

A
  • Acetylcholine gets released and triggers contraction of muscle cell
  • But it never shuts down
  • Prevents relaxation of the muscles
  • Spastic paralysis
  • Muscles are continually clenched
  • Lock jaw
67
Q

What do the influenza viruses contain?

A

Enveloped viruses with 2 different spike proteins
- Neuraminidase
- Hemagglutinin
H1N1
- Hemagglutinin and Neuraminidase

68
Q

What is antigenic drift?

A
  • Smaller changes over time due to mutations
  • H1 is slightly varied over time
69
Q

What is antigenic shift?

A
  • 2 different viruses infect the same host cell
  • A mix up of their genetic material causes the formation of a brand-new combination of the spike proteins
  • Generates a new virus
  • Explains why the influenza virus is constantly changing

Micro (21 decks)

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