staining lab
in the capsular stain, what does the counterstain dye
the cytoplasm
place the steps of the endospore stain in the correct sequence
1. apply malachite green to smear 2. cover smear with small piece of paper towel 3. steam over water bath 4. rinse 5. apply safranin to smear 6. rinse and blot dry
place these reagents in the proper order of their use in the gram staining technique
1. crystal violet 2. gram's iodine 3. decolorizer 4. safranin
put the following steps in order for performing a smear preparation from a liquid culture
1. label the microscope slide 2. apply loopful of bacterial culture to slide 3. air dry 4. heat fix
why might it be important to perform a gram stain on bacterial cells
as part of the information used to choose an appropriate antibiotic treatment
put the following steps in order for performing a smear preparation from a solid culture
1. label the slide with the name of the organism 2. apply loopful of sterile water to slide 3. add very small amount of organisms to water on slide 4. disperse organisms evenly over the center of the slide 5. air dry 6. heat fix
place the following steps of the capsular stain in the proper sequence
1. place a drop of nigrosin on a clean slide 2. add bacteria to nigrosin and mix 3. spread the mixture over slide and air dry 4. apply crystal violet 5. rinse
match the general type of staining method with its description
1. simple : uses only a single dye to color the cells 2. differential stain : uses two dyes to discriminate between cell types or structures 3. structural stain : assists in the observation of structures external to the cell wall
place the following steps of the acid-fast stain in the proper sequence
1. stain with carbolfuchsin 2. rinse off excess primary stain 3. decolorize with acid alcohol 4. rinse with water to stop the decolorization process 5. counterstain with methylene blue 6. rinse off excess counterstain 7. bolt dry
which of the following can be determined by observing bacteria that have been stained through a light microscope
cellular arrangement, cellular morphology
staining can be used to identify which of the following
cellular structures, cellular arrangement, cell shape
if carbolfuchsin was omitted from the acid-fast stain, what color would acid-fast cells appear
clear
if malachite green was omitted from the endospore stain, the endospores would appear ___ in color
clear
if safranin was omitted from the endospore stain, the vegetative cells would appear ___ in color
clear (colorless)
what outcome could be expected if you forgot the crystal violet step while performing a gram stain
gram positive and gram negative organisms would stain pink
if you forget to use the decolorizer, which cell types will appear purple
gram positive and negative
if safranin was omitted from the endospore stain, what color would the endospores appear
green
in this image, the endospores are ___ in color
green
in order to ensure that dye penetrates the spore coat and stains the endospore, which of the following is needed
heat
when should heat fixation take place during the capsular stain
heat fixation is not required in the capsular stain
which of the following describes the correct sequence of the gram stain procedure
heat-fixed slide; use of crystal violet, iodine, decolorizer, and safranin
which of the following is true regarding proper heat fixation
heating too briefly may result in bacteria not adhering to the slide
which of the following is a significant lipid component of the cell walls of acid-fast bacteria
mycolic acid
gram-___ cell walls contain a thin layer of peptidoglycan whereas gram-___ cell walls contain a thick layer of peptidoglycan
negative, positive
this slide depicts a mixed culture of bacteria that were properly stained using the acid-fast stain. which are more numerous, acid-fast or non-acid-fast cells
non-acid-fast
this slide depicts bacteria that were properly stained using the acid-fast staining technique. the bacteria appear to be ___
non-acid-fast
which of the images depicts a slide that has been properly stained using a simple stain procedure
D
which of the following are functions of the bacterial capsule
adherence, protection
based on their cellular morphology, the red cells on this slide would be referred to as
bacilli
which of the following bacteria genera are capable of producing endospores
bacillus, clostridium
in a negative stain, which of the following is stained
background
which of the following stains do not require heat fixation
capsule stain
if methylene blue was omitted from the acid-fast stain, non-acid-fast cells would be ___ at the end of the staining process
clear
the capsule staining technique begins with a ___ stain
negative
what is used as the mordant in the gram staining technique
gram's iodine
if malachite green was omitted from the endospore stain, vegetative cells would appear ___ in color
pink
if you decolorize for more than 30 seconds, gram positive organisms will most likely appear ___ in color
pink
in this image, the figure on the left represents a gram ___ cell wall whereas the figure on the right represents a gram ___ cell wall
positive; negative
the name of the counterstain, or secondary stain, typically used in gram stain technique is
safranin
in a differential staining technique, the stain that is used after the decolorization step is called the counterstain, or ___ stain
secondary
which of the following provides a quick and effective method used to visualize and determine bacterial morphology and arrangement
simple stain
to prepare a ___, a sample of bacteria is taken from a culture and spread onto a clean microscope slide
smear
which occurs first in the endospore stain
staining of the endospore
the organism in the slide exhibit a cellular arrangement known as
staphylococcus
spherical cells arranged in a chain are called
streptococci
the morphology and arrangement of the organism represented in the image would be characteristic of the genus
streptococcus
what is stained by the initial dye in the capsular stain procedure
the background
you have just performed an acid-fast stain, and all of the cells appear to be blue. which of the following could explain your results
the bacteria are non-acid-fast
why is heat fixation not part of the protocol for the capsule stain
the capsule may be damaged
which of the following descriptions reflects observations of a capsular stain that may have been heat fixed
the capsules cannot be seen clearly on the slide
which of the following structures makes it difficult to stain endospores
the endospore coat
what could happen if heat fixation was performed prior to doing a capsular stain
the heat might alter the morphology of the bacteria
which of the following describes the correct method for heat fixation
the heating should be very brief . passing the slide through the flame for 3-5 seconds is enough
this image shows the results of an endospore stain performed on an endospore-producing strain of bacteria. identify which step in the endospore stain was omitted in order to get the results depicted in this slide
the primary stain, malachite green was not used
you are observing klebsiella pneumoniae on a slide that has been stained using the capsular staining method; however, you do not see capsules surrounding the cells as you expected. what is the likely reason for this
the slide was heat fixed
which of the following apply to endospores
they are used for surviving adverse environmental conditions
why is it important to air dry the bacteria before they are immobilized by heat fixation
this ensures the optimal preservation of the bacterial morphology
what is the purpose of the smear preparation
to allow for visualization of individual bacteria
what is the purpose of the gram staining technique
to characterize unknown bacteria
which of the following represent consequences of incorrect performance of the decolorization step
- decolorizing too briefly: false positive results - decolorizing for too long: false negative results - decolorizing for too long: removal of carbolfuchsin (primary stain) from all cells
endospores are difficult to stain due to which of the following
- endospores exclude dye - endospores have a thick spore coat
which of the following correctly describe how the gram stain works to color different type of cells
- gram positive cells retain the purple dye mordant complex because of their thick layer of peptidoglycan - gram negative cells are decolorized and stained by the pink/red secondary stain
if organism are washing off of the slide during rinsing of the stain, which step(s) in the smear preparation may have been excluded
- heat fixation - air drying
before bacteria from a solid culture are applied to a slide, a drop of sterile water is typically added to the slide in order to
- help the bacteria spread evenly - reduce the tendency of the bacteria to stick together
a smear preparation that is too light may result in which of the following
- inability to distinguish individual cell morphology - difficulty locating cells to observe
a smear that is too thick will result in which of the following
- inability to distinguish individual cell morphology - poor quality stain results
which of the following are diseases caused by an acid-fast bacterium
- leprosy - TB (tuberculosis)
which of the following clinically important organisms are considered acid-fast
- mycobacterium tuberculosis - mycobacterium leprae
which of the following would lead to an inability to identify the morphology of organisms using a simple stain
- no organisms in sample - the organism has an acid-fast cell wall - more than one organism in your sample
what might be the result of not allowing a slide to air dry sufficiently prior to heat fixation
- the shape and arrangement of the cells may be disrupted - the bacteria may rinse off of the slide - the bacteria could be aerosolized
which of the following would be appropriate for choosing a sample to perform a smear preparation
- use only a small amount of bacteria on the loop - use bacteria from an isolated colony
which of the following are characteristics of simple stains
- used to visualize morphology of bacteria - used to identify cellular arrangement of bacteria
how do you smear a bacterial colony onto the microscope slide
- using the loop, you disperse the bacteria into the water drop on the microscope slide
staining is a commonly used microbiological technique that is used for which of the following
- visualization of microorganisms - differentiation of microorganisms - identification of some bacterial structures
you just performed an acid-fast stain on an acid-fast organism, yet some of the bacteria appear blue and some appear red. which of the following could explain your results
- you have a mixed population of bacteria in which some organisms are acid-fast and some are not - the primary stain was not allowed to stain long enough
which would be the proper amount of time required for methylene blue dye to remain on the bacterial smear during a simple stain
30 seconds to 2 minutes
which of the images shows a simple stained slide that was prepared from the appropriate amount of microbial material
C
in the kinyoun acid-fast staining method, highly concentrated ___ is used to penetrate the cell wall and colorize acid-fast bacterial cells
carbolfuchsin
which of the following could be determined through simple staining of a microbial smear
cell morphology, cellular arrangement
which of the following are terms used to describe the colored dyes applied in the gram staining technique
counterstain, primary stain
what is the primary dye used to the gram staining technique
crystal violet
in a differential staining technique, a ___ is used to remove the primary stain from the bacterial cell
decolorizer
in order to withstand hostile conditions and facilitate survival, some bacteria produce resistant structures known as ___
endospores
omitting the steaming in an endospore stain would result in which of the following
endospores would not take up stain
the simple stain provides enough information about microbe to clearly identify its species
false
if decolorization was omitted from the acid-fast stain, what color would non acid-fast cells appear
pink/red
if methylene blue was omitted from the acid-fast stain, what color would acid-fast cells appear
pink/red
if decolorization was omitted from the acid-fast stain, what color would acid-fast cells appear
red
what is the most likely reason for the poor appearance of the bacteria on this slide
the slide was heat fixed for too long
what is thought to cause gram positive cells to retain the primary stain and the mordant complex whereas gram negative cells are decolorized
the thickness of the peptidoglycan layer
stains are commonly used for all the following except
the treatment of disease
this image likely depicts a gram stained slide
true
two clinically significant genera of bacteria that are capable of producing endospores are clostridium and bacillus
true
how do you smear a bacterial culture onto the microscope glass slide
using the loop, you spread the bacteria onto the center of the microscope slide
bacterial cells that are curved rods or comma-shaped are called ___ whereas helical bacteria are referred to as spirilla or spirochetes
vibrio
there are many types of staining techniques used in microbiology. which of the following is not a commonly used staining technique
wright's stain
___ is used to stain the vegetative cells in the endospore staining procedure
safranin
which of the following is/are the most appropriate way to correctly label the name of an organism on a glass slide
- E. coli
the purpose of heat fixation is to
- adhere the organisms to the slide - inactivate microorganisms placed on the slide
excessive heating during the fixation stage of preparing a smear can lead to which of the following outcomes upon staining
- bacterial cells may show altered morphology - bacterial arrangements may be disturbed
which of the following apply to bacterial smears
- bacterial smears provide scientists with the means to look at microorganisms - preparing smears disperses bacterial cells on a slide so that individual cells can be visualized under the microscope - preparation of bacterial smears is required for bacterial staining procedures
match the staining procedure with its description
- capsule stain : a stain that enables you to effectively visualize a bacterium's glycocalyx - gram stain : a stain that can differentiate between cells that have thick or thin layers of peptidoglycan in their cell walls - acid fast stain : a stain that would be appropriate for cells that contain mycolic acid in their cell walls
which three of the following terms all refer to a similar structure
- glycocalyx - slime layer - capsule
which of the following stains required heat fixation
- simple stain - endospore stain - gram stain - acid-fast stain
encapsulated organisms are difficult to directly stain because
- the capsule is not permeable to stains - the capsule does not react with most stains
what is the purpose of a simple stain
- to determine cell shape and arrangement of the specimen - to visualize bacteria
what is the purpose of a negative stain
- to determine morphological characteristics of the specimen - to visualize a capsule (if present) - to visualize the bacteria
this image depicts the results of an endospre stain performed on a smear of a known endospore-producing bacterial species. which of the following could have led to the results shown here
- too many organisms were used - the primary stain was omitted - the smear was performed from a young culture that was not yet forming endospores
which of the images depict a slide that was prepared from an excessive amount of microbial material
A
which slide shows both vegetative cells and endospores
A
which of the images depicts a slide that has not been properly heat fixed
B
which of the images represents bacilli
B
heat fixation should take place right after which step in a smear preparation
air drying of smeared bacterial cells
which of the following is not a common staining method used for visualization of bacteria
all of the above are commonly used
bacterial cells that are rod-shaped are called
bacillus
which of the following is stained during the first part of the capsule staining procedure
background of the slide
if carbolfuchsin was omitted from the acid-fast stain, what color would non-acid-fast cells appear
blue
which of the following illustrates a properly stained capsular stain
c
excessive heat fixation can cause damage to which of the following structures, lowering the quality of the stained preparation
capsule, cell wall, cell membrane
___ is the initial stain used in the acid-fast stain
carbolfuchsin
based on the image, what step of the capsular stain was omitted
crystal violet
which stain is used to stain the cytoplasm of the cells in the capsule stain
crystal violet
the type of stain designed to show differences between various organisms or cellular structures if referred to as a ___ stain, whereas a ___ stain uses only one dye to stain all cell types
differential, simple
the ___ stain provides critical information about the peptidoglycan structure of the cell wall
gram
what might happen if you omitted the safranin step while performing the gram stain on a mixed culture of gram positive and gram negative cells
gram negative organisms might not be visible
which stain is used to stain the background in the capsule stain
india ink or nigrosin
___ ___ is used to stain the endospore in the endospore staining procedure
malachite green
the counterstain used in the acid-fast stain is ___ ___
methylene blue
the first dye applied in a differential staining technique is referred to as the ___ stain
primary
if you omit the gram's iodine step while performing the gram stain, gram positive cells will most likely be ___ in color
red
gram negative cells appear ___ after gram staining whereas gram positive cells appear ___
red; purple
staining techniques do not provide information on which of the following structures
ribosomes, cell membrane
staining allows for the visualization of bacterial cells because it increases contrast during microscopic imaging
true
a capsule stain was performed, using crystal violet as a primary stain, followed by a water rinse and then nigrosin as a counterstain. as you observe the slide through the microscope, you suspect you made an error. which of the following is the most likely problem with your technique
you should have started with nigrosin as the primary stain and used crystal violet as a counterstain