Gram positive organisms resist decolorization by ethyl alcohol. The large crystal violet-iodine complex is not able to penetrate the peptidoglycan layer, and is trapped within the cell in gram-positive organisms. Conversely, the outer membrane of gram-negative organisms is degraded and the thinner peptidoglycan layer of gram-negative cells is unable to retain the crystal violet-iodine complex and the color is lost.
What is the purpose of using ethyl alcohol or acetone in the gram stain procedure:
21 CFR 606.65 states, "Supplies and reagents shall be used in a manner consistent with instructions provided by the manufacturer."
The correct answer is A. The reagents must be used according to the manufacturer's instructions for use. If the instructions say one or two drops may be used and the facility procedures also allow one or two drops, then there is no problem with the staff members choosing to use two drops.
While equipment must be calibrated, it does not generally influence the number of drops used.
Staff members often ask co-workers and colleagues from other facilities how to perform tasks, but it is the manufacturer's instructions for the operation of equipment and the use of reagents that must be followed.
A laboratory employee who is performing an internal audit of routine ABO and Rh typing procedures notes that a technologist places two drops of Anti-D in a tube, centrifuges the tube for 20 seconds, and reads the reaction using a magnifying mirror. When questioned about the procedure, the technologist indicates that most staff use two drops of Anti-D reagent because the reactions are stronger with two drops. In addition to reviewing the facility procedure manual, what should be done to ensure regulatory compliance?
Which one of the following conditions is NOT associated with hereditary spherocytosis?
Alpha-fetoprotein is a substance typically used in the triple test during pregnancy and for screening chronic liver disease patients for hepatocellular carcinoma.
Increased concentrations of alpha-fetoprotein (AFP) in adults are MOST characteristically associated with:
The term that is used to describe the color in these tubes of CSF is "xanthochromia." Xanthochromia is an abnormal color, usually yellow, orange, or pink, in the supernatant of the CSF sample. It may indicate that a subarachnoid hemorrhage (SAH) has occurred.
Jaundice and icterus both describe a yellowing of the skin, mucous membranes, and eyes. Blood plasma/serum that is deep yellow is also described as icteric.
What term is used to describe the color in these tubes of cerebrospinal fluid (CSF)?
In the laboratory, surfaces must be disinfected for blood spills. What is the most common disinfectant used?
TESTED 31 Jan 2025
