Deck 7: Traditional Cultivation and Identification

Question 1

Increased concentrations of carbon dioxide (CO₂)(5% to 10%)and approximately 15% oxygen (O₂)produce an environmental condition that best suits which type of organism?

A) Aerobes
B) Anaerobes
C) Capnophiles
D) Microaerophiles

Answer 1

C
Various types of microorganisms require different atmospheric conditions.Capnophiles grow best in the presence of increased levels of CO₂.

Question 2

Which medium can be described as containing hemoglobin, hemin (X factor), and the co-enzyme nicotinamide adenine dinucleotide (NAD)(V factor)?

A) Chocolate
B) CNA blood
C) BHI
D) Thioglycollate

Answer 2

A
Chocolate agar contains extra nutrients that are released into the agar by the lysis of the blood additive.These nutrients include hemoglobin, hemin, and NAD.

Question 3

What name is given to the type of hemolysis that produces complete hemolysis and a clearing of the medium?

A) Beta
B) Gamma
C) Alpha
D) Kappa

Answer 3

A
The type of hemolysis described is beta.Complete lysis of erythrocytes causes clearing of the agar.

Question 4

Which category of media can be described as containing specific nutrients required for the growth of particular bacterial pathogens in a patient specimen?

A) Enrichment
B) Supportive
C) Selective
D) Differential

Question 5

Which medium can be described as containing bile salts and dyes (e.g., bromothymol blue, acid fuchsin)to slow selectively the growth of most nonpathogenic gram-negative bacilli found in the gastrointestinal tract and allow Salmonella spp.and Shigella spp.to grow?

A) Thayer-Martin agar
B) MacConkey agar
C) Phenylethyl alcohol (PEA)
D) Hektoen enteric agar

Question 6

In which category of media would blood agar best fit?

A) Selective
B) Differential
C) Selective and differential
D) Supportive only

Question 7

Which category of media can be described as containing one or more agents that are inhibitory to all organisms except those being sought?

A) Enrichment
B) Supportive
C) Selective
D) Differential

Question 8

Which category of media can be described as containing nutrients that support the growth of the most nonfastidious organisms without giving any particular organism a growth advantage?

A) Enrichment
B) Supportive
C) Selective
D) Differential

Question 9

In which category of media would MacConkey agar best fit?

A) Selective
B) Differential
C) Selective and differential
D) Supportive only

Question 10

The role of the agar ingredient in culture medium is to:

A) provide a nutritional base for bacterial metabolism.
B) solidify the medium and provide a stable culture surface.
C) sterilize the medium and prevent contamination.
D) support the growth of only pathogenic organisms.

Question 11

What name is given to the type of hemolysis that produces incomplete hemolysis and a greening discoloration of the medium?

A) Beta
B) Gamma
C) Alpha
D) Kappa

Question 12

To read the hemolytic reaction accurately on a blood agar plate, the technologist must:

A) hold the plate up to the light, and observe the plate with the light coming from behind.
B) hold the plate under the light, and observe the plate with the light coming from the top.
C) hold the plate over a white background.
D) examine the plate using reflected and transmitted light.

Question 13

Which medium can be described as containing crystal violet dye to inhibit the growth of gram-positive bacteria and fungi and allows many types of gram-negative bacilli to grow?

A) Thayer-Martin agar
B) MacConkey agar
C) PEA
D) Hektoen enteric agar

Question 14

Which group of bacteria uses oxygen as a terminal electron acceptor and grows well in ambient air?

A) Aerobes
B) Anaerobes
C) Capnophiles
D) Microaerophiles

Question 15

In which category of media would Löwenstein-Jensen medium best fit?

A) Selective
B) Differential
C) Selective and differential
D) Supportive only

Question 16

Which category of media can be described as containing some factor or factors that allow colonies of one bacterial species or type to exhibit certain metabolic or culture characteristics that can be used to distinguish them from other bacteria growing on the same agar plate?

A) Enrichment
B) Supportive
C) Selective
D) Differential

Question 17

Organisms that have nutritional needs that are relatively complex and require extra media components to be used for growth are called:

A) fastidious.
B) capnophiles.
C) neutrophils.
D) halophiles.

Question 18

Which medium can be described as suppressing the growth of most gram-negative organisms while allowing gram-positive bacteria to grow?

A) Chocolate
B) CNA blood
C) BHI
D) Thioglycollate

Question 19

A bacterial colony can be described as:

A) sufficiently large numbers of a bacterium that can be observable with the unaided eye.
B) derived from many different types of bacterial cells.
C) belonging to different genera and species.
D) having different genetic and phenotypic characteristics.

Question 20

Which medium can be described as a nutritionally rich medium used to grow various microorganisms, either as a broth or as an agar, with or without added blood?

A) Chocolate
B) Colistin, nalidixic acid (CNA) blood
C) Brain-heart infusion (BHI)
D) Thioglycollate

Question 21

Escherichia coli, a member of the family Enterobacteriaceae, was resistant to the antibiotic vancomycin.Which of the following statements explains this discrepancy?

A) The vancomycin disk has most likely expired.
B) Vancomycin should only be used in viral infections, not bacterial infections.
C) The plate is most likely contaminated with another organism.
D) No discrepancy is present. E. coli is resistant to vancomycin.

Question 22

The most medically important bacteria sought in the medical laboratory are cultivated using incubators with temperatures maintained in what range?

A) 35° to 37° C
B) 30° to 35° C
C) 37° to 39° C
D) 25° to 35° C

Question 23

Generation time can be defined as the:

A) time required for a bacterial population to double.
B) time required for a bacterial population to triple.
C) time required for a bacterial population to quadruple.
D) half-life of bacteria.

Question 24

An oxidase test was performed on two organisms for quality control purposes.Pseudomonas aeruginosa and Stenotrophomonas maltophilia tested positive and negative, respectively.Which of the following statements explains this discrepancy?

A) The oxidase reagent is most likely expired.
B) The organisms are most likely old and therefore are not properly reacting.
C) These organisms are poor choices for quality control purposes; both are oxidase-negative organisms.
D) No discrepancy is present. The correct results are obtained.

Question 25

A positive pyrrolidonyl arylamidase (PYR)test was observed on a species of Enterococcus.What color should be observed for this reaction?

A) Purple
B) Red
C) Green
D) Pink

Question 26

A catalase test was performed from a sheep blood agar plate on a colony of streptococci, and bubbling was observed.Which of the following statements explains this discrepancy?

A) Catalase is the inappropriate test to use on colonies of streptococci; therefore the results are invalid.
B) The colony may have been contaminated with sheep red blood cells, causing a false-positive result.
C) The colony was most likely enterococci, not streptococci.
D) No discrepancy is present. Streptococcus is a catalase-positive colony.

Question 27

A candle jar is used to cultivate which type of bacteria?

A) Aerobes
B) Anaerobes
C) Capnophiles
D) Microaerophiles

Question 28

Reduced O₂ (5% to 10%)and increased CO₂ (8% to 10%)produce an environmental condition that best suits which type of organism?

A) Aerobes
B) Anaerobes
C) Capnophiles
D) Microaerophiles

Question 29

Which of the following organisms grows best at 42º C?

A) Streptococcus pneumonia
B) Haemophilus influenza
C) Neisseria gonorrhoeae
D) Campylobacter jejuni

Question 30

Oxidative or fermentative media were set up on an organism suspected of being Pseudomonas aeruginosa.What results would be expected?

A) Yellow in both tubes
B) Green in both tubes
C) Yellow in the open tube and green in the closed tube
D) Green in the open tube and yellow in the closed tube