What can go wrong during Gram staining?
The rank of errors is:
- Over decolourisation.
- Mixed cultures.
- Misread stains.
- Aged subcultures.
- Disorganisation.
- Inadequate fixation and Insufficient culture.
Sep 27, 2020
What are some factors that affect the accuracy of the Gram stain?
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.
What are two mistakes you could make that would make a Gram stain less reliable?
Choose two mistakes that you could make that would make a Gram stain less reliable. Putting too much dye and leaving it on too long.
What happens if you fail to add iodine when performing a Gram stain?
Failure to add iodine. The Crystal Violet would be leeched out of everything, because the Iodine is what cross-links with the Crystal Violet. And that cross-link is what help the stain to stay within the cell during 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 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 step in the Gram stain procedure 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 three common sources of Gram stain inconsistency?
List the three sources of inconsistent/incorrect Gram Staining:
- over decolorize/under decolorize w/alcohol.
- inconsistency in preparation of emulsion.
- waiting more than 24 hours.
What step of the Gram stain is most likely to cause poor results if done incorrectly?
the decolorization step Excessive Decolorization It is clear that the decolorization step is the one most likely to cause problems in the Gram stain. The particular concerns in this step are listed below. Heat fixing the cells, when done to excess, alters the cell morphology and makes the cells more easily decolorized.
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 are several sources of error in conducting Gram stains?
Sources of Error For example, the Gram stain will not detect organisms that exist within host cells (such as Chlamydia), organisms with no cell wall (such as Mycoplasma, Ureaplasma, and Rickettsia), and bacteria that are too small to be seen with light microscopy (such as Treponema).
What are the common errors in staining methods?
The types of errors were categorized into:
- Misread stains (positive stains misread as negative and vice versa).
- Mixed cultures.
- Using subcultures that were aged (plated out >24 hours).
- Over decolourisation.
- Inadequate fixation (e.g. iodine solution is too weak).