Microbial Pathogenicity Flashcards

1
Q

What are the important microbial pathogens?

A

Viruses, fungi, prions, protozoa, helminths and bacteria

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2
Q

What can viruses cause?

A

H1N1 influenza virus (single stranded RNA, enveloped)

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3
Q

How is H1N1 influenza virus described?

A

Easily spreads and is rarely fatal

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4
Q

What can fungi cause?

A

Tricophyton spp. (ringworm)

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5
Q

What is trichophyton spp.?

A

A colony of fungi growing on the skin which produces legions

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6
Q

What can prions cause?

A

Kuru

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7
Q

What is kuru?

A

A degenerative brain disease caused by a misfiled protein (prion)

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8
Q

How do prions reproduce?

A

When pathogenic prions interact with a normal prion, it mutates the normal one. chain reaction

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9
Q

What can protozoa cause?

A

Plasmodium spp. (malaria parasites)

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10
Q

What can helminths cause?

A

Ancylostoma duodenale (hook worm)

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11
Q

What can bacteria cause?

A

Bacillus Anthracis

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12
Q

What is bacillus anthracis?

A

A gram positive, endospore forming rod shaped bacterium

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13
Q

What is the forms of bacillus anthracis?

A

Cutaneous anthrax and inhalation anthrax

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14
Q

What is cutaneous anthrax?

A

Infects the skin (papule>ulcer>eschar)

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15
Q

What is inhalation anthrax?

A

If spores enter lungs (mediastinal lymphadenopathy)

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16
Q

What do gram positive bacteria have?

A

Thick cell walls that consist primarily of peptidoglycan

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17
Q

What does gram positive bacteria do in the stain?

A

Traps and retains crystal violet stain

18
Q

What do gram negative bacteria have?

A

Cell walls with two layers (a thin peptidoglycan layer and a thick outer membrane that contains polysaccharides bonded to lipids)

19
Q

What do gram negative bacteria do in the stain?

A

Do not retain the stain, crystal violet is easily rinsed away

20
Q

What is koch’s postulates?

A

Guidelines used to demonstrate that a specific pathogen causes specific disease symptoms

21
Q

Where must the pathogen be present (koch’s postulates)?

A

In every individual with the disease

22
Q

What can a sample of the microorganism taken from the diseased host do (Koch’s postulates)?

A

be grown in pure culture

23
Q

What can a sample of the pure culture do (koch’s postulates)?

A

Cause the same disease when injected into a health host

24
Q

What can the microorganism do (koch’s postulates)?

A

Be recovered from the experimentally infected host

25
Q

What are the exceptions to koch’s postulates?

A

Microbes that can’t be cultured (treponema pallidum) and pathogens that can also be found in healthy subjects and don’t produce the same symptoms (vibrio cholera)

26
Q

What happens before the key stages of microbial pathogenesis?

A

Exposure to the pathogen

27
Q

What is the first stage of microbial pathogenesis?

A

Adherence to host cells (skin or mucous)

28
Q

What happens after adherence to host cells?

A

Invasion of host tissues (through epithelium)

29
Q

What happens after invasion of host tissues?

A

Replication within the host tissue (fast so immune system can’t act on it)

30
Q

What happens after replication within the host tissue?

A

Disease causing damage to host tissues (pathology)

31
Q

What can disease causing damage to host tissues be caused by?

A

Toxicity and invasiveness

32
Q

How can toxicity cause damage to host tissues?

A

Toxin effects are local or systematic

33
Q

How can invasiveness cause damage to host tissues?

A

Further growth at original sites and distant sites

34
Q

What are the bacterial virulence factors for adherence to host cells?

A

Adhesions such as fimbria (bind to cells) e.g. neisseria gonorrhoeae

35
Q

What are the bacterial virulence factors for invasion of host tissues?

A

Motility (move through mucus) (flagella) and internal-related proteins (InIB)

36
Q

What are the bacterial virulence factors for replication within host tissues?

A

Siderophores (bind iron) the siderophore yersinia actin solubilises metal bound to host proteins and transports it back to the bacteria.

Capsules (resist phagocytosis)

37
Q

What are the bacterial virulence factors for disease causing damage to host tissue?

A

Endotoxins which cause inflammation and exotoxins which an be fatal

38
Q

What are endotoxins and exotoxins?

A

Toxic virulence factors

39
Q

What are endotoxins?

A

Lipopolysaccharide (LPS) components found in the outer membrane of gram negative bacteria (released after bacteria is destroyed/dies) and elicit a strong immune response. e.g. neisseria gonorrhoeae (causes inflammation)

40
Q

What are the possible effects of endotoxin Lipid A?

A

Fever, blood clotting, inflammation and shock

41
Q

What are exotoxins?

A

Produced within the living bacteria and then released into the surrounding medium

42
Q

What are the three types of exotoxins?

A

Cytotoxins (destroy red blood cells), neurotoxins (effect the nervous system) and enterotoxins (effect the gut)