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Old 06-28-2011
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Bacteria AFB features!

A patient with a cavitary lung lesion coughs up sputum that contains thin, acid-fast positive rods. Which of the following features would most likely be associated with these bacteria?
A. Nutritional requirement for factors V and X
B. Streptokinase
C. Toxic shock syndrome toxin
D. Visible under dark field illumination
E. Waxy envelope
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Old 06-28-2011
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Quote:
Originally Posted by earthpole View Post
A patient with a cavitary lung lesion coughs up sputum that contains thin, acid-fast positive rods. Which of the following features would most likely be associated with these bacteria?
A. Nutritional requirement for factors V and X
B. Streptokinase
C. Toxic shock syndrome toxin
D. Visible under dark field illumination
E. Waxy envelope
E. Waxy envelope for mycolic acid in cell wall???
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Old 06-28-2011
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Originally Posted by pass7 View Post
E. Waxy envelope for mycolic acid in cell wall???
Yes that's right.

That's the reason they can't be stained by H&E.
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Old 06-28-2011
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Default E

the pt has TB.. So E.
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answer is E
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Old 06-28-2011
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Mycobacteria, such as the causative organism of this patient's tuberculosis, are "acid fast" because they have an envelope that contains large amounts of lipids and even true waxes (unlike envelopes of other types of bacteria) that prevents the acid-fast stain (carbolfuchsin) from leaking out.The other characteristics listed in the answers are commonly tested features of specific bacteria:Nutritional requirement for factors V and X (choice A) is a feature of Haemophilus influenzae.
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