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q......? - cilastatin
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11-10-2011, 12:56 PM
with an appropriately performed acid-fast staining procedure, staphylococcus epidermidis will appear
a. Blue b. Red c. Purple d. Colerless e. Brown please choose the answer and explain.. thank you
11-10-2011, 01:18 PM
A. Blue, because Staphylococcus sp doesn't have mycolic acid in their outer membrane (like TB), so the stains can enter (as well as exit) the cell easily.
1st: with carbol fuchsin + heat: red color 2nd: red color is washed out by alcohol: colorless 3rd: stained blue with methylene blue vs TB 1st: heat is a must to "melt down" mycolic acid to let the carbol fuchsin come inside: red color 2nd: once inside, carbol fuchsin can't be washed out: still red 3rd: without the heat, methylene can't enter the cell: still red. |
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