Microbiology B

Question 1

what does the word microbiota describe?

Answer 1

the word microbiota is used to describe the diverse community of bacteria, fungi, and viruses that reside on and with each of us.

Question 2

what are symbiotic microorganisms?

Answer 2

where both the human body and microbiota benefit

Question 3

what are pathogenic microorganisms?

Answer 3

they promote diseases.

Question 4

list some benefits of a heathy microflora:

Answer 4

• protection from harmful bacteria
• helps to break down (food fibre)
• Produces metabolites that move through
  the body and have beneficial effects on
  metabolism.

Question 5

four factors that can influence the make-up of an individual’s microbiota:

Answer 5

birth, breast fed, rural living or city living, contact with pets, objects, how many people you interact with.

Question 6

what is an opportunistic infection?

Answer 6

an infection caused by a pathogen that takes advantage of an opportunity not normally available.

Question 7

Describe an ‘opportunity’ that a normal microflora microorganism may take advantage of, to become pathogenic?

Answer 7

Host becomes immunocompromised through infection, cancer treatment (radiation or chemotherapy) or immunosuppressive drug treatment.

Question 8

When an individual is exposed to a pathogen, disease may, or may not result.
This depends on:

Answer 8

• the individuals susceptibility to the disease (age, pregnancy, illness, stress)
• the virulence of the pathogen (the ability to infect, invade and cause damage to the host tissue.)
• ability of the pathogen to resist the body’s antibodies, bacteriolytic enzymes and phagocytes, if it is to multiply successfully.

Question 9

what does virulence mean?

Answer 9

virulence is a pathogens ability to cause damage to a host.

Question 10

what is the pathogenicity of an organism?

Answer 10

its ability to cause disease - determined by its virulence factors.

Question 11

why doesn’t an infection always occur?

Answer 11

• the microbe may land in the wrong place/=
• antibacterial factors (lysosomes in tears)
• antibodies may be present
• normal flora may inhibit growth or produce antibacterial factors which have an antibiotic effect
• phagocytes (present in mucus membranes) engulf and destroy the invader
• host resistance

Question 12

what body sites contain no microorganisms?

Answer 12

• brain, blood, spinal fluid, heart

Question 13

what are examples of virulence properties of microorganisms?

Answer 13

• capsules
• enzymes
• exotoxins
• endotoxins

Question 14

and infection that is disseminated throughout the body is called:

Answer 14

systemic

Question 15

antimicrobial agent:

Answer 15

any compound that kills or inhibits microorganisms. (it may be synthetic, semi-synthetic or naturally occurring.

Question 16

selective toxicity:

Answer 16

drug will kill or inhibit the microorganism responsible for the disease without causing damage to the host cells.

Question 17

broad spectrum antimicrobial agents:

Answer 17

antimicrobial agents with a broad range of activity against microorganisms.

Question 18

Narrow spectrum antimicrobial agents:

Answer 18

Antimicrobial agents with a narrow range of activity against many gram positives but not gram negatives.

Question 19

bactericidal:

Answer 19

able to kill bacteria

Question 20

bacteriostatic:

Answer 20

Able to inhibit growth. The body defines mechanisms then eliminate the infection.

Question 21

A good antimicrobial should:

Answer 21

• be toxic to the microorganism but not the host
• cause no allergic reaction in the host
• be stable
• be soluble in body fluids
• be retained in infected tissue long enough to have an effect
• kill the pathogens before they can become resistant to it.

Question 22

6 links of the chain of infection:

Answer 22

1. infectious agent (pathogen)
2. reservoir (the normal location of the pathogen)
3. portal of exit from the reservoir
4. portal of entry into a host
5. susceptible host

Question 23

Infection:

Answer 23

implies that microorganisms capable of causing disease have gained access to body tissues with subsequent establishment and multiplication. This has then led to the production of clinical signs of infection.

Question 24

reservoirs:

Answer 24

these are sites in which viable infectious agents remain alive and from which infection a new host may occur. These may be on-living, inanimate objects or other living animals.

Question 25

Endogenous infections:

Answer 25

The pathogens (infections) may come from another part of the host’s own body (own flora)

Question 26

Exogenous infection:

Answer 26

this originates outside the body and is thus acquired from another person or object.

Question 27

endemic:

Answer 27

a disease which is always present in a population.

Question 28

Pandemic:

Answer 28

an epidemic that spreads worldwide.

Question 29

carriers:

Answer 29

infected individuals not showing obvious signs of clinical disease but are potential source of infection to others.

Question 30

indirect transmission:

Answer 30

may occur (eg. faecal-oral transmission of cholera or typhoid via contaminated water or food.)

Question 31

inanimate reservoirs:

Answer 31

includes air, food, water, soil, fomites. Dust may contain spores and respiratory secretions in which bacteria may be protected with a coat of dried saliva.

Question 32

fomites:

Answer 32

inanimate objects such as stethoscopes, pens, cutlery, surgical eqiupment, books, ect. which may harbour pathogenic microorganisms

Question 33

colonisation:

Answer 33

microorganisms are able to live and reproduce on the human body without causing disease.

Question 34

antiseptic:

Answer 34

a type of chemical disinfectant, suitable for use on skin or living tissue. Used to kill or remove harmful microorganisms without damaging the tissue. May not kill endospores or viruses.

Question 35

aseptic technique:

Answer 35

procedures used to minimise the transfer of microorganisms (sterile or clean technique)

Question 36

pasteurisation:

Answer 36

a method developed to preserve milk and other liquids without altering their taste or quality. Destroys bacteria responsible for spoilage and some pathogens, but not all microorganisms.

Question 37

decontamination:

Answer 37

the removal of possible harmful microorganisms from an object by cleaning or disinfecting

Question 38

detergent:

Answer 38

a solution which washes away dirt and organic matter, may not kill microorganisms, although some may.

Question 39

The temperature and time combination most commonly used to sterilise an item using an autoclave is:

Answer 39

121 degrees celsius for 15 mins.