Week 2 - Microbiology

Question 1

What is a microorganism

Answer 1

An organism/replicating entity that is of microscopic size

Question 1

What is microbiology

Answer 1

The study of micro-organisms (or macroscopic for example some worms) their relationships with humans

Question 2

3 types of cellular microorganisms

Answer 2

Bacteria
Protozoa/other parasites
Fungi

Question 3

2 types of acellular microorganisms

Answer 3

Viruses and prions (are more like deviated proteins)

Question 4

5 features of prokaryotes

Answer 4

No membrane bound nucleus
Transcription and translation are coupled (i.e not in ribosome and nucleus)
Single, circular chromosomal DNA
Additional DNA carried in plasmids
Usually bacteria

Question 5

4 features of eukaryotes

Answer 5

DNA is held in chromosomes inside membrane bound nucleus
Translation and transcription processes are compartmentalised
Cytoplasm is rich in membrane bound organelles
Cellular organisms other than bacteria

Question 6

How is DNA found in bacteria

Answer 6

Long, circular form sometimes with plasmids in addition

Question 7

What else surrounds the membrane around the bacteria

Answer 7

Cell wall
Thick capsule

Question 8

How do bacteria reproduce

Answer 8

Via binary fission (asexual reproduction by separation into 2 bodies)

Question 9

What makes bacteria gram-positive

Answer 9

Thick layer of peptidoglycan on cell wall so crystal violet remains

Question 10

What makes bacteria gram-negative

Answer 10

Thin layer of peptidoglycan on cell wall

Question 11

What makes bacteria gram-stain unreliable

Answer 11

Very small bacteria, atypical life cycle, atypical structure, don’t have complex wall

Question 12

What can be used when bacteria are gram stain unreliable

Answer 12

PCR
Microscopy
Alternative staining/culture techniques

Question 13

What counter-stains the gram negative bacteria

Answer 13

Safranin

Question 14

2 examples of gram positive coccus bacteria

Answer 14

Streptococcus aureus
Streptococcus pneumoniae

Question 15

2 examples of gram positive rods

Answer 15

Listeria monocytogenes
Corynebacterium diphtherie

Question 16

2 examples of gram negative cocci

Answer 16

Nisseria meningiditis/gonnorrhoeae

Question 17

2 examples of gram negative rods

Answer 17

escherichia coli
salmonella species

Question 18

What is a commensal organism

Answer 18

One that uses food supplied internally/externally without establishing a close relationship - mutualistic

Question 19

3 benefits of natural flora from birth

Answer 19

Immune stimulation
Metabolic waste products - vitamins K and B
Competition and natural by-products inhibit the establishment of infection

Question 20

5 sites of colonisation of bacteria

Answer 20

Colon (most diverse and large in number)
Skin
Distal GI tract
Upper resp
Distal urethra

Question 21

Name 7 sterile body sites

Answer 21

Blood, tissue, organ systems
Central nervous system
Exposed conjunctivae
Female reproductive tract down to the cervix
Lower respiratory tract
Sinuses, inner and middle ear
Renal system down to postural urethra

Question 22

Define a parasitic infection

Answer 22

Establishment, persistence and reproduction of an infectious agent at the expense of a host

Question 23

Opportunistic infection

Answer 23

Infection by less virulent infection that ubiquitous in the environment but might cause harm in immunocompromised individuals

Question 24

Nosocomial infection

Answer 24

Hospital acquired infection

Question 25

Carrier state

Answer 25

A host that has an infection that is inapparent throughout it's course and has no symptoms - can be chronic or transient

Question 26

Endotoxins

Answer 26

lipopolysaccharide - forms the outer part of the cell membrane of gram negative bacteria

Question 27

Exotoxins (super antigens)

Answer 27

Produced by gram positive intracellularly and released by mature toxins on infection For example streptococcus aureus streptococcus pyogenes

Question 28

What do exotoxins cause

Answer 28

Non-specific polyclonal T cell stimulation Toxic shock syndrome

Question 29

Factors that determine whether patients will develop an infection

Answer 29

Age Gender Ethnicity Personal hygiene Nutrition Other medical conditions Immunocompromise due to condition or medication Presence of bionic materials e.g plastic/metal - vascular endothelium is designed to reject any bacteria or foreign objects therefore organisms can target these metals and plastics since easy to stick to

Question 30

Why might faecal samples need to be decontaminated

Answer 30

due to diverse flora present

Question 31

Example of testing you might do on faecal sample

Answer 31

latex agglutination to determine whether any antigens or antibodies are present

Question 32

What is sepsis

Answer 32

Physiological response to severe infection when the body responds improperly to infection. Involves cytokine cascades, free radical production and vasoactive mediators

Question 33

Name the 6 forms of cocci

Answer 33

Coccus Diplococci Staphylococci Streptococci Tetrad Sarcina

Question 34

Name 4 forms of bacilli

Answer 34

Simple bacillus Diplobacilli Streptobacili Palisades