Overview conventional cultivation and ID system Flashcards
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
a. Enrichment media
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
c. Combination of supportive and differential
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
d. Chocolate agar
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
a. Inhibits many gram-negative bacilli that are not enteric pathogens
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
b. Beta-hemolysis
What CO2 concentration is achieved when using a candle jar?
a. 1%
b.3%
c.6%
d.9%
b. 3%
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
d. The presence of a particular nucleic acid sequence
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.
b. Identify the single likely gram-negative lactose fermenter as evident by the combined colonial morphology.
T/F:
Selective media contain one or more agents that are inhibitory to most organisms except those being sought
True
T/F:
Most clinically significant gram-negative bacteria are susceptible to the antibiotic vancomycin.
False
T/F:
Any zone of bacterial growth inhibition around a vancomycin-impregnated disk indicates that the bacteria are resistant to the drug
False
Bacteria requiring increased levels of CO2
capnophilic
Bacteria requiring low levels of O2
microaerophilic
Artificial laboratory environment
in vitro
Catalyzes the release of water and O2 from hydrogen peroxide
catalase
Within a living organism
in vivo
Complex nutritional needs
fastidious
Identification of Enterobacteriaceae
oxidase negative
Positive reaction in E. coli
indole
Positive reaction in identification of Neisseria spp.
oxidase
Grows in presence or absence of O2
facultatively anaerobic
Used to differentiate gram-positive cocci
PYR
What is a biophasic medium, and how is it used?
A bacterial culture growth media consisting of both a solid agar and liquid phase, often used in blood cultures
_____________ is inhibitory or lethal for strictly anaerobic bacteria
Oxygen
What is the main purpose for using a culture medium that will meet the bacterial cell growth requirements?
Ensuring that the cell will multiply to sufficient numbers to allow visualization by the unaided eye to aid in the identification of the bacteria
What is the first and most important step for bacterial identification and characterization?
Selection of a pure colony derived from a single bacterial cell
Lack of sufficient water from media is deleterious to bacterial growth in what two ways?
- Less water is available for essential bacterial metabolic pathways
- 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.
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
- gram-positive cocci
- gram-negative cocci
- gram-positive bacilli
- gram-negative bacilli.
The term pleomorphic means exhibiting various shapes, gram-negative coccobacilli, or gram-variable bacilli
