Diagnostic Bacteriology

Question 1

What colour does gram negative stain

Answer 1

Purple

Question 2

What colour does gram positive stain

Answer 2

Pink

Question 3

What is the composition of the membrane of gram negative

Answer 3

2 outer membranes Has got lipopolysaccharide

Question 4

What is the composition of the membrane of gram positive

Answer 4

1 outer membrane - cytoplasmic membrane Thick peptidoglycan

Question 5

How do you stain the bacteria

Answer 5

Apply crystal violet

Iodine added to form complexes larger than crystal violet

Wash with alcohol (dehydration and peptidoglycan become tightened)

Question 6

What is a cocci bacteria

Answer 6

Spheres

Question 7

What is a bacilli bacteria

Answer 7

Round ended cylinders

Question 8

What shape is staphylococci

Answer 8

Grapes

Question 9

What shape is streptococci

Answer 9

Long chains

Question 10

What is hemolytic activity good at differentiating

Answer 10

Gram positive bacteria such as staphylococcus, streptococcus and enterococcus

Question 11

What does hemolytic test mean

Answer 11

Ability of microorganisms to produce hemolysins (enzymes that damage red blood cells)

Question 12

What does gamma hemolysis

Answer 12

No hemolysis (no zone)

Question 13

What does alpha hemolysis mean

Answer 13

Partial hemolysis (opaque zone)

Question 14

What does beta hemolysis mean

Answer 14

Complete hemolysis (transparent zone)

Question 15

What is lactose fermentation good for

Answer 15

Useful for differentaiting gram negative bacteria

Question 16

How does lactose fermentation work

Answer 16

Include bile salts, crystole violet and lactose

See if bacteria can ferment lactose

Question 17

What is the test result of lactose fermentation

Answer 17

It produces lactic acid

It is pink

Question 18

What is catalase test useful in determine

Answer 18

Straphylococci - produces catalase

Streptococci - does not produce catalase

Question 19

What does catalase break down

Answer 19

Hydrogen peroxide

Produces water and oxygen

Question 20

What does coagulase test for

Answer 20

Discriminate between staphylococci

Aureus - produces coagulase

Other staphylococci - no coagulase

Question 21

What does coagulase do

Answer 21

Processes prothrombin to thrombin

15 seconds

Question 22

What bacteria is:

gram positive

catalase negative

a hemolytic

Answer 22

S. pneumoniae

S. mutans

Question 23

What bacteria is:

gram positive

catalase negative

b hemolytic

Answer 23

S. agalactiae

S.pyogenes

Question 24

What bacteria is:

gram positive

catalase negative

y hemolytic

Answer 24

E. faecium

E. faecalis

Question 25

What bacteria is:

gram positive

catalase positive

coagulase positive

Answer 25

S.aureus

Question 26

What bacteria is:

gram positive

catalase positive

coagulase negative

Answer 26

S. epidermidis

S. saprophyticus

Question 27

What bacteria is

gram negative

diplococci

Answer 27

N. gonorrhoeae

N. meningitidis

N. catarrhalis

Question 28

What bacteria is:

gram negative

coccobacilli

Answer 28

H. influenzae

B. pertussis

Question 29

What bacteria is:

gram negative

bacilli

lactose fermenting

Answer 29

E. coli

K. pneumoniae

E. cloacae

Question 30

What bacteria is:

gram negative

bacilli

lactose non-fermenting

Answer 30

P. aeruginosa

Salmonella