Microbiology

Question 1

Pathogen Definition

Answer 1

Organism that causes or its capable of causing disease

Question 2

Commensal definition

Answer 2

Organism which colonises the host but causes no disease in normal circumstances

Question 3

Opportunist pathogen definition

Answer 3

Microbe that only causes disease if host defences are compromised

Question 4

Virulence / pathogenicity definition

Answer 4

the degree to which a given organism is pathogenic

Question 5

Asymptomatic carriage definition

Answer 5

When a pathogen is carried harmlessly at a tissue site where it causes no disease

Question 6

What shape are cocci and bacillus bacteria

Answer 6

Cocci - round
Bacillus - rod

Question 7

What stains differentiate gram +ve and -ve bacteria and results

Answer 7

Gram stain
Blue - Positive
Pink - Negative

Question 8

Describe the structure of a bacteria

Question 9

What type of bacteria does not stain with gram stain? What stain does it require?

Answer 9

Mycobacteria - Ziehl-Neelsen stain

Question 9

What type of bacteria does not stain with gram stain? What stain does it require?

Answer 9

Mycobacteria - Ziehl-Neelsen stain

Question 10

Differences between gram positive and gram negative bacteria

Answer 10

+ve - large amount of peptidoglycan and phospholipid membrane

-ve - 2 phospholipid membranes (inner and outer) with thin peptidoglycan layer. Also contains lipopolysaccharide (endotoxin).

Question 11

Bacteria environment

Answer 11

-80 –> 80 degrees (120 for spores)
pH 4-9
Water / desiccation 2 hours - 3 months (50+ years spores)
UV light

Question 12

What is an endotoxin

Answer 12

Component of the outer membrane of gram negative bacteria - lipopolysaccharide

Question 13

What is an exotoxin

Answer 13

Secreted proteins of gram positive and negative bacteria

Question 14

Types of genetic variation in bacteria

Answer 14

Mutation
Base Substitution
Deletion
Insertion

Gene Transfer
Transformation via plasmid
Transduction via phage
Conjugation via sex pilus

Question 15

Types of gram positive cocci and how to differentiate

Answer 15

Staphylococci clusters and Streptococci chains

Question 16

Type of coagulase positive gram positive bacteria cluster

Answer 16

Staphylococcus aureus

Question 17

Type of coagulase negative gram positive bacteria cluster

Answer 17

S.epidermis

Question 18

How are streptococcus categorised

Answer 18

Haemolytic group A or B or non

Question 19

Type of alpha haemolytic optochin sensitive gram positive chain

Answer 19

S.pneumoniae

Question 20

Type of alpha haemolytic optochin resistant gram positive chain

Answer 20

Viridans strep

Question 21

Type of beta haemolytic antigenic group A gram positive bacteria chain

Answer 21

S.pyrogenes

Question 22

Type of beta haemolytic antigenic group B gram positive bacteria chain

Answer 22

S.aglactinae

Question 23

Type of non haemolytic gram positive bacteria chain

Answer 23

S.mutans

Question 24

Types of aerobic gram positive bacilli

Answer 24

Listeria monocytogenes Bacillus anthracis - Spore forming anthrax Corynebacterium diphtheriae - metachromatic granules causing diphtheria

Question 25

Types of anaerobic gram positive bacilli

Answer 25

C.tetani - tetanus C.botulinum - paralysis spreading from head to body C.difficile - antibiotic associated diarrhoea