bacterial pathogenicity

Question 1

what is the definition of a pathogen?

Answer 1

an organism capable of causing disease

Question 2

what is the definition of a commensal?

Answer 2

an organism part of the normal flora

Question 3

what is the definition of pathogenicity?

Answer 3

the ability to cause disease

Question 4

what is the definition of virulence?

Answer 4

the ability to cause severe disease

Question 5

describe the stages in the lifecycle of a parasite

Answer 5

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

Question 6

what are microorganisms?

Answer 6

agents of infectious disease

Question 7

what effect do most microorganisms have on humans?

Answer 7

none, most microorganisms are harmless for humans

Question 8

what are the divisions of microorganisms?

Answer 8

• bacteria
• fungi
• viruses
• prions
• parasites

Question 9

what is colonisation?

Answer 9

when microbes find a new host and start to multiply

Question 10

what is another term for microorganisms?

Answer 10

microbes

Question 11

what is the normal flora?

Answer 11

a balance developed between colonised microbes and humans

Question 12

what is the term used if a microbe causes disease?

Answer 12

infection

Question 13

what is the term used if an infection’s source of microbe is patient’s own flora?

Answer 13

endogenous infection

Question 14

what is the term used if an infection’s source of microbe is from outside the patient’s body?

Answer 14

exogenous infection

Question 15

what is a primary pathogen?

Answer 15

microbes that always cause disease in a new susceptible human

Question 16

what is an opportunistic pathogen?

Answer 16

microbes that cause disease only in immunocompromised patients eg microbes from normal flora

Question 17

what is the microbes carrier state?

Answer 17

when the microbe remains in the human body for some time after infection

Question 18

overview of bacterial infections

Question 19

innate immune system vs normal flora

Question 20

what is the germ theory of disease?

Answer 20

• 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

Question 21

what are roots of microbial entry?

Answer 21

• ingestion
• inhalation
• injection
• across mucous membranes
• into ear
• transplacental

Question 22

what is an example of microbial entry via ingestion?

Answer 22

salmonella

Question 23

what is an example of microbial entry via inhalation?

Answer 23

tuberculosis

Question 24

what is an example of microbial entry via injection?

Answer 24

hep B

Question 25

what is an example of microbial entry via mucous membranes?

Answer 25

trepomena pallidum

Question 26

what is an example of microbial entry via the ear?

Answer 26

pseudomonas aeruginosa

Question 27

what is an example of microbial entry via transplacental?

Answer 27

cytomegalovirus

Question 28

what are sources of microbial entry?

Answer 28

Person-to-person - Contaminated blood or other bodily fluids - Touch - Saliva - Air Fomites (objects) Insects Water Food

Question 29

describe a prokaryotic cell?

Question 30

what is the method of attatchement of bacteria?

Answer 30

pili (hairlike) - proteinaceous - overcome mechanical forces - specificity to host and tissue

Question 31

describe UTIs

Answer 31

urinary tract infection - very common in women - colonise from faeces

Question 32

what is the host protection from uti's?

Answer 32

- flushing action of urine

Question 33

how does the bacteria in UTIs persist against urine?

Answer 33

- Bacteria produce specialised adhesive structures to circumvent flushing action - Adheres to bladder mucosal cells - E. coli usually isolated

Question 34

what is incapsulated bacteria?

Answer 34

bacteria covered with a polysaccharide capsule- related to immune response

Question 35

give an example of a encapsulated infection

Answer 35

meningitis

Question 36

what is the capsular function?

Answer 36

Mediate adhesion Immune evasion Protection from desiccation (drying out) Reserves of carbohydrate Encapsulated bacteria give rise to smooth colonies Capsule material gives rise to ‘capsular antigens’

Question 37

where are exotoxins produced?

Answer 37

inside most gram- POSITIVE bacteria

Question 38

where are endotoxins produced?

Answer 38

wall of gram- NEGATIVE bacteria

Question 39

endotoxin??

Question 40

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