Gram + bacteria

Question 1

what is used as artificial mesia

Answer 1

agar plates

Question 2

what is the first classification of bacteria

Answer 2

obligate bacteria or

bacteria that may be cultured on artificial media

Question 3

shapes of bacteria

Answer 3

rods
cocci
spirochaetes

Question 4

what is ZN stain positive

Answer 4

special stain due to waxy coating found on the bacteria

Question 5

gram +

Answer 5

purple
thick peptidoglycan layer
(has plasma membrane, pehiplasmicspace, peptidoglycan)

Question 6

gram -

Answer 6

pink
LPS outer membrane
(plasma membrane, periplasmic space, peptidoglycan, outer membrane)

Question 7

what is coagluase

Answer 7

enzyme produced by bacteria that clots blood plasma

- fibrin clot formation around bacteria may protect from phagocytois

Question 8

which species are important in opportunistic infections

Answer 8

coagulase (enzyme which clots blood plasma)

Question 9

how does staph aureus spread

Answer 9

aerosol and touch

Question 10

what agar is selective for gram +

Answer 10

mannitol salts agar

Question 11

what happens with s aureus on mannitol

Answer 11

s aureus ferments mannitol

Question 12

virulence factors of staph aureus

Answer 12

pore forming toxins
enterotoxin
toxic shock syndrome
protein A

Question 13

pore forming toxins examples and what they do

Answer 13

a-haemolysin and panton valetine leucodidin

PVL causes haemorrhage pneumonia by inserting into membrane, cell collapse and haemorrhage out

Question 14

proteases

Answer 14

exfoliatin

breaks down junctions between skin cells

Question 15

toxin shock syndrome

Answer 15

stimulates cytokine release

host responce

Question 16

protein A

Answer 16

surface protein which binds IGs in the wrong direction

Question 17

what is a coagluseae negative staphylococci

Answer 17

staph epidermidis

- opportunistic pathogen

Question 18

staph epidermis main virulence factor

Answer 18

ability to form persistent biofilms

- difficult to remove sticky ECM

Question 19

biofilm definition

Answer 19

• mass of bacteria, usually heterogeneous, found adhered to surfaces, encased in extracellular polysaccharide matrix

Question 20

types of haemolysis

Answer 20

A partial
B complete lysis
no lysis (gamma)

Question 21

A partial haemolysis

Answer 21

greening
h2O2 reacts with Hb
forms met haemoglobin

Question 22

what is haemolysis

Answer 22

enzymes breaking open RBC in agar

Question 23

B complete lysis (haemolysis on the agar plate what happens and what does it look like on the agar)

Answer 23

releases haemolysins O andS

forms circular bands

Question 24

ways to classifify streptococcci

Answer 24

haemolysis

lancefield typing

Question 25

what is lancefeild typing (serogrouping)

Answer 25

method of grouping catalase negative bacteria based on bacterial carbohydrate surface antigens

Question 26

serogrouping and how to test

Answer 26

``` carbohydrate cell surface antigens 1) A-H 2) K-V antiserum added to each group to a suspension of bacteria clumping indicated recongitin ``` ``` A and B most important in pathogens A - S pygenes, important pathogen B - S agalactiae - involved in neonatal infections ```

Question 27

complications with s pyrogen infections

Answer 27

can lead to rheumatic fever glomerulonephritis

Question 28

rheumatic fever

Answer 28

- inflammatory disease of heart, joints, skin, brain - often follows strep throat infection - antibody cross reactivity

Question 29

glomerulonephritis

Answer 29

- inflammatory disease sometimes following S.pyogenes infection

Question 30

anti SLO ttire

Answer 30

(allows risk assessment) Looks for the amount of Anti streptolysin O in the body - antibody against SLO SLO - causes beta haemoloysis ASLO reacts with SLO to neutralise haemolytic activity the anti SLO titre is where there is still prevention of haemlysis - i.e. before it goes red

Question 31

anti SLO titter rapid test

Answer 31

Clumping reaction - streptococcal exoenzymes bound to biologically inert latex particles - if streptococcal antibodies present in the test sample, reaction occurs - presence of an ASO titre of >200 IU/mL in the serum leads to agglutination of the latex particles

Question 32

S pyogens virulence factors

Answer 32

erythrogenic toxin C carbohydrate M protein (inhibits binding) Streptolysin O ASO titre

Question 33

violence factors of S pneumoniae

Answer 33

capsule (antiphagocytic) IgA protease cytotoxin (pneumolysin for lysis)

Question 34

viridian's streptococci

Answer 34

Collective name for oral streptococci - alpha or non haemolytic - some cause caries and abscesses - optochin resistant

Question 35

what is used to test of penumoniae

Answer 35

optochin test

Question 36

how does C diphtheria spread

Answer 36

droplet spread

Question 37

what can C diphtheria grow in

Answer 37

presence of potassium tellutire | selective method of isolating this bacteria from throats of pts

Question 38

toxins of C diptheria

Answer 38

- inhibits protein synthesis (inactivates elongation factor 2 in host cells by additn ADP ribosyl group to aa diphthamide)

Question 39

toxin recognition test

Answer 39

- Toxin recognition (Elek plate) – filter paper soacked in antitoxin which difuses out onto plate, streak samples accorss the middle – if you have toxin in sample it will react with the anti toxin – gives lines when they react

Question 40

how is c diptheria prevented

Answer 40

vaccine