Overview conventional cultivation and ID system

Question 1

BCYE is an example of which type of media?

a. Enrichment media
b. Supportive media
c. Combination of selective and enrichment media
d. Differential media

Answer 1

a. Enrichment media

Question 2

CNA media with blood is an example of which type(s) of media?

a. Enrichment only
b. Supportive only
c. Combination of supportive and differential
d. Combination of selective and supportive

Answer 2

c. Combination of supportive and differential

Question 3

Which type of enrichment media is used to isolate Neisseria and Haemophilus organisms?

a. Hektoen eneric agar
b. Todd-Hewitt broth
c. Regan Lowe agar
d. Chocolate agar

Answer 3

d. Chocolate agar

Question 4

XLD (xylose-lysine-deoxycholate) agar

a. Inhibits many gram-negative bacilli that are not enteric pathogens
b. Inhibits gram-positive organisms
c. Contains a phenol red indicator that detects increased acidity from carbohydrate
d. Causes fermentation

Answer 4

a. Inhibits many gram-negative bacilli that are not enteric pathogens

Question 5

The complete clearing of media around bacterial colonies on a blood agar plate is referred to as:

a. Alpha-hemolysis
b. Beta-hemolysis
c. Gamma-hemolysis
d. Delta-hemolysis

Answer 5

b. Beta-hemolysis

Question 6

What CO2 concentration is achieved when using a candle jar?

a. 1%
b.3%
c.6%
d.9%

Answer 6

b. 3%

Question 7

The following are all bacterial phenotypic characteristics except:

a. Microscopic morphology and staining characteristics
b. Environmental requirements for growth
c. Nutritional requirements and metabolic capabilities
d. The presence of a particular nucleic acid sequence

Answer 7

d. The presence of a particular nucleic acid sequence

Question 8

A clinical isolate was plated to sheep blood, MacConkey, and chocolate agars and incubated at 37°C for 24 hours. Th e initial plate reading identifi ed medium sized, gamma-hemolytic, shiny gray colonies on sheep blood agar; small pink colonies on MacConkey agar; and medium sized, tan, shiny colonies on chocolate agar. Th e most likely next action for the microbiologist is:

a. Identify the two different organisms that are growing on the plates as indicated by the size differences on the agar.
b. Identify the single likely gram-negative lactose fermenter as evident by the combined colonial morphology.
c. Report as normal microbiota without a further biochemical identification.
d. Reinoculated the isolate from the blood and the MacConkey agar plates to two more sets of primary media to provide a better preliminary identification of the isolate.

Answer 8

b. Identify the single likely gram-negative lactose fermenter as evident by the combined colonial morphology.

Question 9

T/F:

Selective media contain one or more agents that are inhibitory to most organisms except those being sought

Answer 9

True

Question 10

T/F:

Most clinically significant gram-negative bacteria are susceptible to the antibiotic vancomycin.

Answer 10

False

Question 11

T/F:

Any zone of bacterial growth inhibition around a vancomycin-impregnated disk indicates that the bacteria are resistant to the drug

Answer 11

False

Question 12

Bacteria requiring increased levels of CO2

Answer 12

capnophilic

Question 13

Bacteria requiring low levels of O2

Answer 13

microaerophilic

Question 14

Artificial laboratory environment

Answer 14

in vitro

Question 15

Catalyzes the release of water and O2 from hydrogen peroxide

Answer 15

catalase

Question 16

Within a living organism

Answer 16

in vivo

Question 17

Complex nutritional needs

Answer 17

fastidious

Question 18

Identification of Enterobacteriaceae

Answer 18

oxidase negative

Question 19

Positive reaction in E. coli

Answer 19

indole

Question 20

Positive reaction in identification of Neisseria spp.

Answer 20

oxidase

Question 21

Grows in presence or absence of O2

Answer 21

facultatively anaerobic

Question 22

Used to differentiate gram-positive cocci

Answer 22

PYR

Question 23

What is a biophasic medium, and how is it used?

Answer 23

A bacterial culture growth media consisting of both a solid agar and liquid phase, often used in blood cultures

Question 24

_____________ is inhibitory or lethal for strictly anaerobic bacteria

Answer 24

Oxygen

Question 25

What is the main purpose for using a culture medium that will meet the bacterial cell growth requirements?

Answer 25

Ensuring that the cell will multiply to sufficient numbers to allow visualization by the unaided eye to aid in the identification of the bacteria

Question 26

What is the first and most important step for bacterial identification and characterization?

Answer 26

Selection of a pure colony derived from a single bacterial cell

Question 27

Lack of sufficient water from media is deleterious to bacterial growth in what two ways?

Answer 27

1. Less water is available for essential bacterial metabolic pathways
2. An increase in the solute concentration of the media as a result of the loss of water can osmotically shock the bacterial cell and cause lysis.

Question 28

Most clinically relevant bacteria can be divided into four groups based on their gram stain appearance; what are these four groups? What does the term pleomorphic

Answer 28

1. gram-positive cocci
2. gram-negative cocci
3. gram-positive bacilli
4. gram-negative bacilli.

The term pleomorphic means exhibiting various shapes, gram-negative coccobacilli, or gram-variable bacilli