Which step is most likely to cause poor results in the Gram stain?
the decolorization step Excessive Decolorization It is clear that the decolorization step is the one most likely to cause problems in the Gram stain.
What is the most common source of errors during the Gram stain procedure?
In this study, we present a review of over 6,000 Gram-stains and establish an error rate of around 3%, with the most common reason for error being an over-decolourisation step resulting in organisms that should be Gram-positive appearing as Gram-negative.
What is the most critical and difficult step in the Gram stain Why?
the decolorizer step is the most critical because too much destaining reagent can remove the dye-mordant complex from the cells, which makes the gram-positive cells appear to be falsely gram-negative.
How can Gram staining go wrong?
Several factors may affect the results of Gram staining: If the smear is too thick, proper decolorizing will not be possible. If the smear is overheated during heat fixing, the cell walls will rupture. Concentration and freshness of reagents may affect the quality of the stain.
Which step in the Gram stain is most prone to error if done incorrectly How might that step affect the end result?
The decolorization of the cells is the most “operator-dependent” step of the process and the one that is most likely to be performed incorrectly. Rinse with water to stop decolorization.
What are the common errors in staining procedure?
The rank of errors is:
- Over decolourisation.
- Mixed cultures.
- Misread stains.
- Aged subcultures.
- Disorganisation.
- Inadequate fixation and Insufficient culture.
Jul 5, 2022
Why might Gram staining fail sometimes?
Gram-positive bacteria may lose their ability to retain crystal violet and stain Gram negatively for the following reasons: Cell wall damage of bacteria due to antibiotic therapy or excessive heat fixation of the smear. Over- decolorization of the smear.
What factors may cause a false Gram reaction to be observed?
Gram stain may not falsely reveal organisms in the following scenario:
- Use of antibiotics before collecting a specimen.
- Inappropriate age of culture: too young or too old.
- Fixing the smear before its dry.
- The smear is too thick.
- Low concentration of crystal violet.
- Excessive heat fixation.
- Excessive washing between steps.
Why is decolorization the most critical step in Gram staining?
The length of decolorization is a critical step in gram staining as prolonged exposure to a decolorizing agent can remove all the stains from both types of bacteria.
Which is the most critical step in differentiating Gram positive bacteria from Gram negative bacteria?
The Gram stain is the most important staining procedure in microbiology. It is used to differentiate between gram positive organisms and gram negative organisms. Hence, it is a differential stain.
Why is the Gram stain not always successful?
Old cultures tend to lose the peptidoglycan cell walls, which predisposes gram-positive cells to be gram-negative or gram variable. Gram stain is not useful for organisms without a cell wall like Mycoplasma species, and for smaller bacteria like Chlamydia and Rickettsia species.
Why is decolorization important in Gram staining?
The length of decolorization is a critical step in gram staining as prolonged exposure to a decolorizing agent can remove all the stains from both types of bacteria.
Which factors can affect the results of a Gram stain and why?
The many variables that can affect this stain are age of the culture, amount of decolorizer used, the time of decolorization, the type of organism (acid-fast bacteria and spores do not stain well), thickness of the smear, and the general care of the stainer.
Which step is the most crucial or most likely to cause poor results in the Gram stain why quizlet?
Which step is the most crucial or most likely to cause poor results in the Gram stain? Why? Grams decolorizer is the most crucial step in staining. Over decolorization may be a result of over decolorizing and cause your stain to be gram-staining.
What error in Gram staining procedure could result in Gram-positive bacteria appearing pink?
The removal of the lipid layer allows the leaching of the crystal violet stain from the cells. When the counter stain of safranin is added the decolorized gram-negative bacteria stain pink. In contrast, the solvent dehydrates the thicker gram-positive cell walls, closing the pores as the cell wall shrinks.
Which is the most critical step in differentiating Gram positive bacteria from Gram-negative bacteria?
The Gram stain is the most important staining procedure in microbiology. It is used to differentiate between gram positive organisms and gram negative organisms. Hence, it is a differential stain.
Which step of the Gram stain is critical for differentiating between Gram-positive and Gram-negative cells Why is this step differential?
Both gram + and – bind to the crystal violet: the key step to their differentiation is the decolorization.
What happens if the iodine step is skipped in Gram staining?
If the Gram's iodine step was omitted from the Gram staining procedure, you would expect Gram-positive bacteria to appear ( Select ) and Gram-negative bacteria to appear ( Select ) because, in the absence of iodine, the ( Select ) wouldn't be properly fixed within the bacterial cells.
Which is the most critical step in differentiating Gram-positive bacteria from Gram-negative bacteria?
The Gram stain is the most important staining procedure in microbiology. It is used to differentiate between gram positive organisms and gram negative organisms. Hence, it is a differential stain.
Why is the most critical step in Gram staining is the Decolorizing?
The length of decolorization is a critical step in gram staining as prolonged exposure to a decolorizing agent can remove all the stains from both types of bacteria. The final step in gram staining is to use basic fuchsin stain to give decolorized gram-negative bacteria pink color for easier identification.
What might cause a false gram positive result?
Inappropriate specimen sampling, specimen processing, smear preparation, and prior antibiotic therapy are all factors that can have an adverse impact on Gram stain result. The inherent nature of some organisms may also produce misleading results; for example, Acinetobacter spp.
What happens if you forgot the decolorization step?
If the decolorization step were omitted, both types of cell walls would retain the primary stain, which is crystal violet.
What would happen if you skipped the safranin step of the Gram stain?
If the safranin step were skipped, none of the cells would take up a pink color. This would not explain why the Gram-positive cells were pink instead of purple.
Which step of the Gram stain is critical for differentiating between Gram-positive and Gram negative cells Why is this step differential?
Both gram + and – bind to the crystal violet: the key step to their differentiation is the decolorization.
What are likely false results in Gram staining?
Positive Gram stains with negative culture results could be due to fastidious or nonviable organisms and failure to order appropriate testing, such as anaerobe cultures. False-negative Gram stains could occur due to inadequate specimen or smear preparation or failure to examine an adequate number of fields.
Why is decolorization the most important step in Gram staining?
The length of decolorization is a critical step in gram staining as prolonged exposure to a decolorizing agent can remove all the stains from both types of bacteria.
Which is the most crucial step in the performance of the Gram staining procedures explain?
The thickness of the smear used in the Gram stain will affect the result of the stain. The step that is most crucial in effecting the outcome of the stain is the decolorizing step.
What would happen if you forgot the decolorization step?
If the decolorization step were omitted, both types of cell walls would retain the primary stain, which is crystal violet.
What would be the causes of a false positive result in a Gram stain?
Even occasional false-positive Gram stains should prompt review of laboratory methods. Our observations implicate dead bacteria in microbiologic reagents as potential sources of false-positive Gram stains.
Which of the statements regarding Gram staining is wrong?
Answer. Explanation: Mycobacterium tuberculosis can't be visible with Gram staining because it has techoic acid in its cell wall which make it resistant from Gram staining.