Microbiology

Question 1

Define the term microbiology

Answer 1

The science of microorganisms (any organism too small to be seen by the naked eye)

Question 2

What are the 4 basic groups of microbes which can all cause healthcare associated infections?

Answer 2

1. bacteria
2. viruses
3. fungi
4. protozoa

Question 3

What is the structure of a prokaryotic (bacteria) cell?

Answer 3

-has no distinct nucleus
-genetic information stored in plasmids and singular chromosomes

Question 4

Give 3 examples of common bacterial infections

Answer 4

-salmonella
-E.coli
-MRSA

Question 5

What are the nutritional requirements that bacteria cells need?

Answer 5

-food
-water
-carbon dioxide
-neutral or alkaline conditions
-obligate aerobes (require oxygen for aerobic respiration)

Question 6

What are the 3 basic shapes that bacteria are classified into?

Answer 6

1. coccus (circular)
2. rod or bacillus
3. spiral (spirochete)

Question 7

What are the 4 types of coccus bacterium?

Answer 7

1. single coccus
2. paired coccus (diplococcus)
3. chains or streptococcus
4. bunches or staphylococcus

Question 8

Give 3 examples of fungal infections

Answer 8

-thrush
-athletes foot
-aspergillus

Question 9

What is the structure of viruses?

Answer 9

Have either DNA or RNA but never both, contained within a capsule

Question 10

Give 3 examples of viral infections and state the tissues that they infect

Answer 10

(can only replicate inside a living cell)

-cold virus = upper respiratory tract
-influenza virus = upper respiratory tract and lungs
-chicken pox = nerve endings

Question 11

What are the 3 ways that virus’ effect the host cells?

Answer 11

1. infecting the cell and killing it
2. has no effect but remains potentially infectious
3. transformation of cell into malignant form

Question 12

What is the microorganism protozoa?

Answer 12

A unicellular microbe which inhabits mainly soil and water which can cause severe disease

Question 13

Give 3 examples of protozoal infections (with detail)

Answer 13

-malaria (plasmodium malariie infects and destroys RBC)
-cryptosporidium (from infected drinking water causing diarrhoea & fever)
-amoebic dysentery (from entamoeba histolytic from infected drinking water)

Question 14

What is pathogenesis?

Answer 14

The development of a disease

Question 15

What 3 things does pathogenesis do to humans?

Answer 15

1. disruption to tissues
2. production of toxins
3. produces large and harmful immune responses from the body

Question 16

What 5 things determine the virulence (severity) of a disease?

Answer 16

1. invasiveness of the bacteria (its ability to invade tissues and multiply rapidly)
2. toxigenicity of the microorganism
3. its immunogenicity
4. how good the organism is at evading the immune system
5. its ability to live outside the body and survive transport

Question 17

What evidence may a human display showing that they have an infection?

Answer 17

-a fever (38 degrees +)
-pain
-discharge of pus or other bodily fluids
-increase in white blood cells
-loss of function
-general malaise (discomfort)
-inflammation response (pain, swelling, heat, redness)

Question 18

What actions do antibiotics bring about in a bacterium cell?

Answer 18

-block metabolism
-block DNA replication
-block protein synthesis
-inhibit cell wall synthesis

Question 19

What is the name of the process in which bacteria reproduce rapidly?

Answer 19

Binary fission

Question 20

How can antibiotic resistance occur?

Answer 20

-bacterial transformation (resistant gene passed on)
-conjugation (resistant gene directly given)
-transfection (type of plasmid transformation)
-spore formation

Question 21

What are antiviral agents and how do they work?

Answer 21

-as viruses use human cells in order to function it is hard to find drugs which target the virus without harming other human cells
-some drugs exploit the fact that the virally infected cell produce some unique enzymes in order to produce new virus particles
-drugs include interferon and AZT

Question 22

What are antifungal agents and why are they rarer and more toxic to the host?

Answer 22

-fungal pathogenicity occurs because the fungi disrupt tissues or cells, produce toxins or create large and harmful immune responses
-fungal cells are similar to human cells therefore drugs are rarer and more toxic
-e.g clotrimazole

Question 23

What does a commensal relationship mean?

Answer 23

one organism living in close association with another, such that one organism benefits without harming the other