Microbiology 1

Question 1

What are examples of microorganisms?

Answer 1

a microscopic organism

bacteria 
viruses
fungi
algae
protozoa

Question 2

What are pathogenic microbes?

Answer 2

microbes that cause disease

an infection is the invasion and growth (multiplication) of microbes in an individual or population (host organism)

Question 3

What is microbial flora?

Answer 3

normal body flora
- microorganism that live on a living organism without causing disease

• microorganisms that reside on the surface and deep layer of the skin, in the saliva, oral mucosa and gastrointestinal tracts of every human being

Question 4

What are the benefits of microbial flora?

Answer 4

prevent humans from being colonised by harmful bacteria

Question 5

What are the four classes of microorganism?

Answer 5

hazard group 1
hazard group 2
hazard group 3
hazard group 4

Question 6

What is hazard group 1?

Answer 6

a biological agent that is unlikely to cause human disease

biological agent

• microorganism
• cell culture
• human endoparasites = parasite that lives in the internal organs and tissue of its host

Question 7

What is the difference between an endoparasite and an ectoparasite?

Answer 7

endoparasite

• a parasite that lives inside the body of the host = in the internal organs and tissues
• cause infection inside the body

ectoparasite

• a parasite that lives on the outside of the host
• cause infection superficially within the skin

Question 8

What is hazard group 2?

Answer 8

a biological agent the can cause disease and may be a hazard to employees

it is unlikely to spread through the community

there is usually an effective prophylaxis and treatment available

Question 9

What is hazard group 3?

Answer 9

a biological disease that can cause severe human disease and presents a serious hazard to employees

it may present a risk of spreading to the community

there is usually an effective prophylaxis or treatment available

Question 10

What is hazard group 4?

Answer 10

a biological agent that causes severe human disease and is a serious hazard to employees

it is likely to spread to the community

there is usually no effective prophylaxis or treatment available

Question 11

What are the three main potential routes of infection?

Answer 11

inhalation
- breathing in aerosol or vapour mist

ingestion

• poor hygiene practise
• via eating and drinking

skin penetration

• open wound
• contact with mucus membrane of eyes and/or mouth

Question 12

What is a serial dilution?

Answer 12

a process of taking a sample and diluting it through a series of standard volumes of serial diluent

concentration decreases by the same factor in each step

estimates the concentration of an unknown sample

Question 13

What does microbemia, viremia, bacteremia and fungemia mean?

Answer 13

microbemia - infections caused by microorganisms that enter the circulatory system

bacteremia - presence of bacteria in the blood
viremia - presence of viruses in the blood
fungemia - presence of fungi or yeasts in the blood

Question 14

What are the steps in causing an infection?

Answer 14

transmission
adhesion
penetration
spread
survival in host

Question 15

What are the three ways bacteria escape the immune system?

Answer 15

modulate (modify) the cell surface

release proteins in the host which degrade/inhibit the host immune system

avoid/hide from the immune system within cells

Question 16

Whats is intracellular pathogenesis?

Answer 16

parasites that are capable of growing and reproducing inside host cells

Question 17

What are the two types of intracellular parasites?

Answer 17

facultative intracellular parasite
-can live inside or outside the host cell

obligate intracellular parasite

• cannot exist or reproduce outside the host cell
• require a host cell

Question 18

What is Koch’s Postulates?

Answer 18

consist of 4 principles designed to establish whether a microorganism causes diseases

Question 19

What is the process of the experiment of Koch’s Postulates?

Answer 19

microorganism from an dead animal is isolated

microorganisms are grown in a pure culture
- microorganisms are identified

microorganisms are injected into a healthy animal

the disease is reproduced in a second healthy animal
- microorganism are isolated

microorganisms are grown in a pure culture

identical microorganisms are identified

Question 20

What are the 4 principles of Koch’s Postulates?

Answer 20

bacteria must be present in every case of the disease
- must be the cause

bacteria must be isolated from the host with the disease and grown in a pure culture

specific disease must be reproduced when a pure culture of bacteria is inoculated into a healthy host

bacteria must be recoverable from the experimentally infected host