26malik
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A 16-year-old girl presents to her physician complaining of redness and a yellowish
discharge from her left eye for the past 2 days. She reports minimal crusting upon
awakening and denies eye pain or previous trauma. Upon examination, there is diffuse conjunctival hyperemia associated with a mucoid discharge. The pupils dilate normally, although there is mild photophobia in the affected eye. Gram's stain of the exudate shows pleomorphic, gram-negative bacilli. To culture this organism with whole blood agar, which of the following must be used?
A. Antibiotics to inhibit normal flora
B. Cold temperature
C. Egg yolk cholesterol
D. Reduced oxygen tension
E. Staphylococcus aureus
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| vallia
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E?
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| robin082006
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HI B infection?
E because S.Aureus provides NAD and hemin for its growth
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| 26malik
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The correct answer is E.
The patient is suffering from conjunctivitis caused by Hemophilus, a fastidious organism requiring factors V (nicotinamide adenine dinucleotide) and X (hematin), which must be released from whole blood preparations to be accessible to the organism. This can be done by gentle heating, which lyses the red blood cells, or by co-culture with Staphylococcus aureus, which is beta hemolytic and lyses the red blood cells to provide the factors Hemophilus needs for growth. This is called the satellite phenomenon.
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| giovanni83
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Causes of purulent conjunctivitis:
staf aureus
strep pne
hib
neisseria gon
chlamidia tr
The only one gram neg bac is HAEMOPHILUS INFLUENZAE, that needs staf to be cultured
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| mjl1717
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good concept!
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| bactitech
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If you have chocolate agar, you don't need Staph. aureus for satelliting. This is a trick question :-). Most labs always plate eye specimens to both blood and chocolate.
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