Microbiology Bacteria L14

Question 1

What is microbiology

Answer 1

Study of organisms and agents to small to be seen by the naked eye

Question 2

Acanthamoeba is common in what type of people

Answer 2

Contact lens wearers

Question 3

What are infectious diseases

Answer 3

Infectious diseases are caused by pathogenic microorganisms, such as bacteria, viruses, parasites or fungi; the diseases can be spread, directly or indirectly, from one person to another

Question 4

What do repeated vaccinations do

Answer 4

Enhance the effectiveness of the antibody response

Question 5

How do antibiotics work

Answer 5

They cure diseases by killing or interfering with the growth of bacteria.

Question 6

What are the two types of antibiotics

Answer 6

Some antibiotics selectively only act on a few specific bacteria, others will target a wider range

Question 7

How do superbugs arise

Answer 7

Abuse of antibiotics means that defenceless bacteria are killer and the ones that can resist it are ‘selected’

Question 8

Common examples of superbugs

Answer 8

MRSA and C.difficile

Question 9

What is meant by epidemic

Answer 9

Used to describe an outbreak of an illness of disease in localised area

Question 10

What is meant by Pandemic

Answer 10

When a disease occurs in more than one country or population simultaneously, affecting a lot of people (e.g AIDS/HIV)

Question 11

How can bacteria be classified`

Answer 11

1) Morphological appearance
2) staining characteristics
3) growth requirements
4) antibiotic susceptibility
5) genotype classification

Question 12

What are the three basic shapes of bacteria

Answer 12

1) Cocci, diplcocci (round)
2) bacili (rod-shaped)
3) Spirochetes (spiral)

Question 13

Describe structure of bacteria

Answer 13

1) DNA is organised as a fibrous mass
2) 70s ribosomes consisting of 30s and 50s sub-units
3) Plasma membrane
4) Cell wall made up of peptidoglycan
5) Inclusion bodies which as an energy store

Question 14

How does gram stain work

Answer 14

Bacteria slide is stained with crystal violet and then treated with iodine and finally decolourise with ethanol. Gram positive will retain the stain and gram negative will not

Question 15

How does gram positive bacteria retain the gram stain

Answer 15

The gram stain becomes incorporated in the thick peptidoglycan layer

Question 16

Are gram positive or negative more complex

Answer 16

Gram negative are more complex

Question 17

How do certain bacteria prevent phagocytosis

Answer 17

Certain gram postive and gram negative bacteria have a capsule external to the cell wall

Question 18

Examples of appendages on bacteria

Answer 18

1) Gram negative organisms may be covered by fine hairs (fimbriae) which mediate attachment to host
2) Pili can attach bacterial cells together or transfer genetic information (sex pili)

Question 19

What environment do bacteria exist in

Answer 19

Aerobic (through glycolysis, Krebs cycle and oxidative phosphorylation) and anaerobic (through fermentation yielding

Question 20

What ways can genetic information in bacteria be transferred

Answer 20

1) Transformation (DNA plasmid is inserted into the bacteria)
2) Transduction (bacteriophage infects a a bacteria cell)
3) Conjugation (Donor bacteria cell attaches onto recipient bacteria cell with a pilus)

Question 21

Genetic information in bacteria exists where

Answer 21

In the bacterial chromosome and on extrachromosomal plasmids

Question 22

What is located on plasmids

Answer 22

Antibiotic resistance

Question 23

What is a bacteriophage

Answer 23

A virus that infects bacteria

Question 24

Whats special about bacterial spores

Answer 24

Highly resistant against different environments and can protect against heat, radiation or dessication

Question 25

Examples of spores

Answer 25

Clostridium tetani that produces tetanus and Bacillus anthracis causing anthrax

Question 26

What do commensals (normal flora) do

Answer 26

Protect against infection by competing with potential pathogens for nutrients or preventing them for colonising epithelial surfaces

Question 27

What can alterations in homeostasis trigger

Answer 27

It may trigger pathogenic damage to the body

Question 28

Different types of bacteria

Answer 28

1) Pathogenic
2) Bacteria which are part of the normal flora which sometimes acquire extra virulence factors making them pathogenic
3) Some bacteria from the normal flora can cause disease if they gain access to deep tissues
4) Bacteria that affect immunocompromised patients

Question 29

Two types of immunocompromised patients

Answer 29

1) Acquired through disease (e.g AIDS)

2) Steriods/corticoids drugs

Question 30

Two types of way bacteria can invade a body

Answer 30

1) Colonise on the surface of the body and then release toxins into the body
2) Invade the body and subsequent multiplication in tissues

Question 31

What is virulence

Answer 31

Degree of pathogenicity

Question 32

What are Virulence factors

Answer 32

Factors that trigger pathology

Question 33

How can toxins cause damage

Answer 33

Inhibiting protein synthesis, damaging cell membranes, induction of inflammation, inhibition of opsonisation and killing of white blood cells

Question 34

Difference between endotoxins and exotoxins

Answer 34

Endotoxins are bound to cell surface whereas exotoxins are excreted or released during bacterial lysis

Question 35

What do antimicrobial agents

Answer 35

Kill or inhibit bacterial growth by interfering with cell wall synthesis, DNA synthesis, protein synthesis and folic acid metabolism

Question 36

What is the most common test for antibiotic susceptibility

Answer 36

A disk diffusion test and using the size of zones of inhibition to work out which antibiotic is the best