mahendra
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A 14-year-old boy is brought to the emergency department by his
parents because of high fever, headache, and stiff neck for the past
36 hours. He has become confused over the course of the morning. He
uses no medications, has no allergies, and is not sexually active.
On examination, he has a temperature of 38 C, moderate nuchal
rigidity, and marked photophobia. Lumbar puncture is performed,
and the cerebrospinal fluid shows: WBC 3500 with 95% PMNs, elevated
protein, decreased glucose, and gram-positive cocci in pairs and
short chains. By which of the following mechanisms does this
organism mediate its attachment to the respiratory mucosa?
A. Production of a C carbohydrate
B. Production of a hemolytic exotoxin
C. Production of a hyaluronic acid capsule
D. Production of an IgA protease
E. Production of an M protein
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| asmi
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i think of pneumococci C
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| mahendra
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its wrong
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| asmi
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E FOR SURE
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| drmka
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The mojor pathogenic protein is M protein of Streptococci.İn order to cause a disease organism must attach pharingeal mucosa,M protein is facilitate this way.....
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| asmi
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YES I WAS CONFUSED WITH PNEUMOCOCCI
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| mahendra
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This is a case of Streptococcus pneumoniae meningitis. This organism is able to attach to the respiratory mucosa because it has teichoic acids in its envelope, and because it produces an IgA protease. The IgA protease physically cleaves the immunoglobulin molecules, leaving the Fc parts to coat the bacterium. This allows the organisms to bind to the Fc receptors on various mucosal cells.
Streptococcus pneumoniae does not produce a C carbohydrate (choice A), and thus cannot be grouped by the Lancefield terminology.
Although the organism does produce the pneumolysin, which is an alpha-hemolytic exotoxin (choice B), this toxin mediates damage to the respiratory epithelium and inhibition of leukocytic responses, not attachment to the mucosa.
Streptococcus pneumoniae does not produce an hyaluronic acid capsule (choice C); Streptococcus pyogenes does. Most capsules serve to inhibit phagocytosis, rather than to mediate adhesion.
Only the group A Streptococci possess an M protein (choice E), which is used to "type" them and helps inhibit phagocytosis.
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| asmi
Forum Hero
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so it means IgA protease is the answer.
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| drmka
Forum Junior
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The bacteries that are seen in CSF made short chains that is the clue,i think...
the answer is E,i think....
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