Microlab - Week 5

Question 1

Is the serological test for influenza A/B trustworthy?

Answer 1

No

Question 2

What serological test did we perform in lab?

Answer 2

EIA

Question 3

What does EIA test for?

Answer 3

the presence of an antigen or antibody within a sample

Question 4

MacConkey agar

Answer 4

selective media for gram negative bacteria

bile salts prevent gram positive bacteria from growing

Question 5

What is MacConkey agar differential for?

Answer 5

lactose fermenters

lactose fermenters stain pink on MacConkey

Question 6

What makes blood agar differential?

Answer 6

differential based on ability to lyse RBCs

Question 7

How can you describe hemolytic activity on blood agar?

Answer 7

alpha, beta or gamma

Question 8

CNA blood agar

Answer 8

selects for gram positive bacteria

differential for blood hemolysis

Question 9

Why is MacConkey agar selective for enterobacteria (gut bacteria)?

Answer 9

bile salts and crystal violet in media are hydrophobic which normally disrupts bacteria membranes

BUT enterobacteria have long hydrophilic molecules on LPS called O-antigens

the hydrophilic O-antigens repel the hydrophobic disrupts away, allowing enterobacteria to grow on MacConkey agar

Question 10

What test can differentiate between Staphylococci and Streptococci?

Answer 10

Catalase test

Question 11

How are Staphylococci and Streptococci similar?

Answer 11

both are gram positive

Question 12

How are Staphylococci and Streptococci different?

Answer 12

streptococci is catalase negative

staphylococci is catalase positive

Question 13

catalase

Answer 13

an enzyme that rapidly decomposes two molecules of H2O2 to water and oxygen

important for organisms that live in oxygen-rich environments

deals with reactive O2 species

Question 14

What two tests can differentiate streptococcus pneumoniae from other gram-positive alpha-hemolytic streptococci?

Answer 14

1) ???
2) bile solubility test

Question 15

Desrcribe streptococcus penumoniae

Answer 15

gram-positive

alpha-hemolytic

Question 16

bile solubility test

Answer 16

determines ability to lyse in prescence of bile salts

streptococcus pneumoniae has LytA-amidase which makes it the only strain that lyses itself and emulsifies by reacting with bile salts

Question 17

Kirby-Bauer disc test

Answer 17

tests for antibiotic suspectibility

can tell you the susceptibility / resistance of bacteria to antibiotic based on size of zone where no growth occurs (Zone of Inhibition)

Question 18

E-test

Answer 18

uses a pre-definded antibiotic gradient to determine the MIC of different antimicrobial agents as tested on agar media

Question 19

MIC

Answer 19

mean inhibitory concentration of an antimicrobial to stop bacterial growth

Question 20

What test is diagnostic standard for detecting Streptococcus pneumoniae?

Answer 20

Abbot BinaxNOW rapid test

Question 21

Abbot BinaxNOW rapid test

Answer 21

tests for streptococcus pneumoniae

tests for pneumococcal C-polysaccharide antigen in urine

Question 22

AbbotBinaxNOW test advantage

Answer 22

quick

Question 23

AbbotBinaxNOW test limitations (3)

Answer 23

1) time to identification
2) prior antibiotic treatment
3) bacterial autolysis