Bacterial pathogenicity Flashcards

1
Q

What is a pathogen

A

An organism capable of causing disease

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2
Q

What is a commensal

A

An organism that is part of the normal flora

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3
Q

What is pathogenicity

A

The ability to cause disease

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4
Q

What is virulence

A

The ability to cause severe disease

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5
Q

What is the simple life cycle of a parasite

A

Enter​
Attach​
Colonise​
Evade host immunity​
Produce harmful proteins​
Disseminate​
Release from host​

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6
Q

What are the subdivisions of microorganisms

A

Bacteria​
Fungi​
Viruses​
Prions​
Parasites ​

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7
Q

What is microbiology

A

The study of microscopic organisms; sub-disciplines include virology, mycology, parasitology, and bacteriology

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8
Q

What are some flora found in the nasopharynx

A

Streptococci
Candida
Neisseria

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9
Q

What normal flora are found on skin

A

Streptococci
Staphylococci
Yeasts

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10
Q

What flora are found in the lower bowel

A

Bacteroides
Clostridium

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11
Q

What flora are found within the vagina

A

Candida
Lactobacilli
Corynebacteria

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12
Q

What is colonisation

A

When microbes find a new host and start to multiply

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13
Q

What is an endogenous infection

A

An infection caused by the patient’s own flora

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14
Q

What is an exogenous infection

A

Infection from external flora

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15
Q

What is the difference between primary and opportunistic pathogens

A

Microbes that always cause disease in a new susceptible human are called primary pathogens while microbes that cause disease only in immunocompromised patients are called opportunistic pathogens

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16
Q

What is the carrier state

A

The continued presence of an organism (bacteria, virus, or parasite) in the body that does not cause symptoms, but is able to be transmitted and infect other persons

17
Q

What is bacterial colonisation

A

The presence of bacteria on a body surface (like on the skin, mouth, intestines or airway) without causing disease in the person

18
Q

What is the germ theory of disease

A

The microbe must be present in every case of the disease​

The microbe must be isolated from the diseased host and grown in pure culture​

The disease must be reproduced when a pure culture is introduced into a susceptible host​

The microbe must be recovered from an experimentally infected host​

19
Q

Who created the germ theory of disease

A

KOCH’S POSTULATES (1890)

20
Q

How can diseases be spread

A

Person-to-person​
-Contaminated blood or other bodily fluids​
-Touch​
-Saliva​
-Air​

​Fomites​
Insects​
Water​
Food​

21
Q

What features pf a prokaryotic cell are usual

A

Cell envelope
DNA
Cytoplasmic membrane
Ribosomes

22
Q

What MAY be present in a prokaryotic cell

A

Capsule
Inclusion granules
Frimbriae (pilli) (gram -ve)
Flagellum
Membranous invagination

23
Q

Defence against UTIs

A

Main defence is flushing action of urine

Tamm-Horsfall protein helps bind specific Escherichia coli strains and remove them

24
Q

What are some encapsulated infections

A

Meningitis, pneumonia, otitis media and sinusitus

25
What is the function of a bacterial capsule
Mediate adhesion​ Immune evasion​ Protection from desiccation​ Reserves of carbohydrate​ Encapsulated bacteria give rise to smooth colonies​ Capsule material gives rise to ‘capsular antigens’​ - strep infections
26
What are endotoxins
Produced inside mostly Gram -ve bacteria as part of their growth and metabolism They are secreted and released following lysis into the surrounding medium
27
What are endotoxins
Part of the outer portion of the cell wall or Gram -ve bacteria They are liberated when bacteria die and the cell wall breaks apart
28
What is the point of LPS (endotoxin)
Promotes production of platelets, clotting factors, mast cells, macrophages, inflammatory response etc These responses when uncontrolled can lead to hypertension and toxic shock which can result in death
29
Lethal bacterial proteins (exotoxins)
Botulinum 0.6x10-8 (mouse) Tetanus 4x10-8 (mouse) Shigella toxin 2.3x10-6 (rabbit)
30
Difference between endo and exo toxins
ENDO Lipopolysaccharide Outer membrane Not very potent Low specificity Pyrogenic EXO Protein Extracellular (diffusible) Highly potent Very specific Occasionally pyrogenic
31
Virulence factors
Fimbriae (pilli) -adhesion Capsule -protection/camouflage Flagella -Chemotaxis, Penetration LPS/Endotoxin -endotoxic shock/ inflammation