Intro

Question 1

define pathogen

Answer 1

Organism that causes or is capable of causing disease

Question 2

define commensal

Answer 2

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

Question 3

define opportunist pathogen

Answer 3

Microbe that only causes disease if host defences are compromised

Question 4

define virulence/ pathogenicity

Answer 4

The degree to which a given organism is pathogenic

Question 5

define asympomatic carriage

Answer 5

Disease is carried harmlessly at a tissue site

Question 6

what is bacterial nomenclature

Answer 6

genus then species

Question 7

what is round bacteria called

Answer 7

coccus

Question 8

what is rod like bacteria called

Answer 8

bacillus

Question 9

two main groups of bacteria

Answer 9

gram positive
gram negative

Question 10

gram positive colour?

Answer 10

purple

Question 11

gram negative colour?

Answer 11

pink

Question 12

what is diplococcus

Answer 12

two cocci that grow together

Question 13

structure of basic bacteria cell

Answer 13

cell envelope- phsopholipid membrane w layer of peptidoglycan
capusle
inner membrane
outer membrane

Question 14

purpose of flagella/ pilli

Answer 14

to stick to host cells
swim / movement

Question 15

what bacteria does not show up with GRAM staining and what would you use isntead

Answer 15

TB
Ziehl- neelsen stain

Question 16

structure of gram + bacteria

Answer 16

Has a capsule with
Thick peptidoglycan linked to phospholipid membrane

Question 17

structure of gram - bacteria

Answer 17

two phospholipid membrane
perisplamsic space- thin phosphilipid layer
endotoxin-

Question 18

what is endotoxin

Answer 18

Component of the outer membrane of bacteria, eg lipopolysaccharide in Gram negative bacteria

Question 19

what is exotoxin

Answer 19

Secreted proteins of Gram positive and Gram negative bacteria

Question 20

characteristics of exotoxin

Answer 20

protein
specific
labile to heat
strong antigenicity
produced by gram + & -

Question 21

methods of gene transfer

Answer 21

transformation
transduction
conjugation

Question 22

what does gram staining do

Answer 22

seperates bacteria into gram positive and negative depending on the thickness of peptidoglycan

Question 23

what structure does staph usually appear

Answer 23

clusters

Question 24

what structure does strep usually appear in

Answer 24

chains

Question 25

what does the catalase test show

Answer 25

differentiates between staphylcoccus and streptococcus genus

Question 26

what would catalase + show

Answer 26

staph

Question 27

what would catalase -ve show

Answer 27

strep

Question 28

3 types of haemolysis and what they show

Answer 28

alpha- partial beta- complete gamma- none

Question 29

what does mackonkey agar show

Answer 29

bacteria that can digest lactose

Question 30

examples of bacteria that are non- fermenters gram -ve

Answer 30

salmonella, shigella, pseudomonas aurerginosa

Question 31

optochin -ve and +ve would show

Answer 31

-ve = strep viridans +ve= strep pneumonia

Question 32

which strep is susceptible to optochin

Answer 32

s pneumoniae

Question 33

structure of c difficile

Answer 33

gram +ve bacilli

Question 34

what does the coagulase test do

Answer 34

differentiates staph aureus which produces the enzyme coagulase from S epidermis and S saprophyticus which do not produce coagulase

Question 35

what would coagulase +ve show

Answer 35

staph aureus

Question 36

what would coagulase -ve indicate

Answer 36

staph epidermis or sapro

Question 37

method for the coagulase test

Answer 37

apply rabbit plasma to a small sample or pure colony, observe for fibrin clot clumps

Question 38

what does the lancefield grouping rely on ?

Answer 38

relies on the different group specific carbohydrates antigen present on the bacterial cell wall

Question 39

what group in the lancefield classification would s.pyogenes be

Answer 39

GROUP A

Question 40

what agar would you use for streptocuccus

Answer 40

blood

Question 41

what agar would you use for fastidious neisseria

Answer 41

chocolate

Question 42

what agar would you use for differentiating lactose status

Answer 42

MacConkey

Question 43

what agar would you use to isolate salmonella and shigella

Answer 43

XLD AGAR- xylose lysine deoxycholate agar

Question 44

What diseases does s pyogenes cause

Answer 44

Tonsillitis Pharyngitis Impetigo Cellulose of the foot