Infection 1 Intro To Infection

Question 1

Infection definition

Answer 1

Invasion of a host’s tissues by microorganisms

Question 2

An infection is a disease caused by…

Answer 2

Microbial multiplication
Toxins
Host response

Question 3

Ways people get infections

Answer 3

Patient to themselves
Other organisms
Environment

Question 4

How do patients get infections from themselves ?

Answer 4

The normally harmless microbiota transfer to other sites which are harmless

E.g. harmless on skin but damaging if enter into bloodstream via a cut

Question 5

Microbiota meaning

Answer 5

Microorganisms in particular place??

Question 6

How do other organisms cause infections

Answer 6

Direct e.g. STIs (other people) - HIV, chlamydia
Indirect e.g. air-chickenpox, influenza, covid
vector-malaria

Question 7

How does the environment cause infections?

Answer 7

• Ingestion of contaminated food or water e.g. cholera, salmonella
• Inhalation of contaminated air
• Contact with contaminated surfaces e.g. hep B, sharing needles/ medical instruments

Question 8

Horizontal transmissions of infection

Answer 8

Contact: direct, indirect, vectors
Inhalation: droplet, aerosols
Ingestion

Question 9

Vertical transmission of infection

Answer 9

Mother to child
Before or after birth
Via placental blood vs breast feeding

Question 10

How to microorganisms cause disease?

Answer 10

1- exposure
2- adherence of microorganisms to cell surface
3- invasion
4- multiplication
5- dissemination

Question 11

Dissemination meaning

Answer 11

Spreading

Question 12

What are virulence factors?

Answer 12

Chemical products of the pathogen that allow it to successfully survive and reproduce in a host - harming them

Question 13

What are endotoxins?

Answer 13

Part of cell wall in lipopolysaccharide protein complexes in gram negative bacteria

Question 14

What do endotoxins do?

Answer 14

Cause host cell damage
Either directly or due to a virulence factor which causes damage

Question 15

What is a specific investigation for?

Answer 15

To identify organism causing infection

Question 16

What is a supportive infection for?

Answer 16

To say ‘yes the patient has an infection’

Question 17

List some supportive investigations

Answer 17

FBC
C-reactive protein
Blood chemistry - liver +kidney function tests
Imaging - X-ray, ultrasound, MRI
Histopathology

Question 18

List specific investigations

Answer 18

Bacteriology
Virology

Question 19

Difference in the outer membrane/cell wall of gram positive + negative bacteria

Answer 19

• gram positive: peptidoglycan cell wall
• gram negative: lipopolysaccharide/endotoxin

Question 20

What are exotoxins?

Answer 20

Proteins that are secreted by gram positive + negative bacteria

Question 21

General rule of gram positive cocci

Answer 21

Strep + staph bacteria

Question 22

General gram positive bacilli

Answer 22

Clostiroides

Question 23

General gram negative cocci

Answer 23

Neisseria
Moraxella