Microbiology 2: Bacterial diseases

Question 1

List the potential sources of infection by bacteria?

Answer 1

Extrinsic - from outside you

Intrinsic - from inside you

Mythical - mythical explanations e.g. catching a cold from being outside in the cold

Upper respiratory tract (intrinsic + extrinsic)

Lower GI tract (intrinsic + extrinsic)

Sexual/Urogenital tract (intrinsic + extrinsic)

Skin (intrinsic + extrinsic)

Nosocomial/Hospital Acquired (all of the above)

Food and Water

Animals

Question 2

List the potential routes (portals of entry) of infection by bacteria?

Answer 2

-upper respiratory tract -urogenital tract -broken skin -the gastro-intestinal tract -‘faeco-oral route’ (contaminated food and water) -Intravenous

Question 3

Name the two types of “portals of entry” and explain them?

Answer 3

Expected-e.g. normal (harmless) microbiota entering via an expected route (newborn infant and maternal microbiota) Un-expected-. normal (harmless) microbiota entering unusual site OR pathogenic microbiota entering any site

Question 4

Define Infectivity?

Answer 4

the ability of a pathogen to spread rapidly from one host to another.

Question 5

Define virulence?

Answer 5

the disease producing ability of a microorganism for example:Toxin production eg Pneumolysin: cholesterol-dependent pore-forming toxin affecting lung architecture Degradation of host molecules eg Hyaluronan lyase- degrades host hyaluronic acid matrix for nutrition and ? spread

Question 6

Define infective dose?

Answer 6

Infectious Dose - number of bacteria required to initiate an infection

Question 7

If a pathogen can kill or subvert phagocytes then their infectious dose is higher or lower?

Answer 7

lower

Question 8

define pathogenicity?

Answer 8

ability to cause DISEASE

Question 9

Name the factors that affect pathogenicity?

Answer 9

Infectivity and Virulence

Question 10

Name the factors that can effect the infectious dose

Answer 10

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Question 11

How are bacterial pathogens of the mouth transmitted?

Answer 11

droplet transmission

Question 12

How can a bacteria be transmitted from the upper respiratory tract to the brains?

Answer 12

Nasal sinuses and into brain

Question 13

In what way is cholera transmitted?

Answer 13

Faeco-oral transmission

Question 14

Name a possible route of transmission to a neonate the involes the Gastro- intestinal tract?

Answer 14

Gastro-intestinal to urogenital tract.. to neonates

Question 15

list the Disease consequences of bacterial pathogens acquired via the upper respiratory tract ?

Answer 15

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Question 16

Name consequences of urogenital tract infection?

Answer 16

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Question 17

Name the consequences of bacterial infection acquired via the GI tract

Answer 17

Diarrhoeal illnesses Bacteremic/systemic infections- typhiod Toxin-mediated disease-Neurological (eg botulism)

Question 18

list the Consequences of infection via broken skin?

Answer 18

Superficial infection Cellulitis Abscess Fasciitis Myositis Gangrene/necrotic infection Bacteremia