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An 8-year-old boy is brought to the emergency room with a 3-day history of fever of 102 degrees F and abdominal pain. He also complains of pain in his right knee and right elbow. He was seen four weeks ago because of a sore throat and a rash. A throat culture performed at that time grew gram-positive cocci in chains. Amoxicillin was prescribed, but the boy's mother did not fill the prescription. On physical examination his temp is 38.7 C (101.7 F), HR is 96, and BP is 100/60. Cardiac examination reveals a pansystolic blowing murmur heard best at the apex. His right elbow is tender on extension and flexion with mild swelling. Laboratory tests reveal a positive C-reactive protein, an ESR of 40 mm/h and a WBC count of 22,000/mm3 with a left shift. ECG shows a prolonged PR interval. Which of the following tests would be positive for the microorganism responsible for this patient's illness?
Options:
A. Catalase test
B. Coagulase test
C. Sensitivity to bacitracin
D. Sensitivity to novobiocin
E. Sensitivity to optochin
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why staph multivit??? it is not subacute endocarditis???
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i think its st, pyogens, but i dont remember sensitivity, lol.
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positive C-reactive protein,ESR,prolonged PR interval
right elbow is tender on extension and flexion with mild swelling(nodule)
murmur.
try now...........
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its strepto,pyogenase,RHD,I think CC is correct
why DD amine?
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yes multivit it is rheumatic fever ( with Jones criteria) i dont know why....i choose D...  )
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The correct answer is C. This case is classic for Rheumatic fever, including two of the major Jones criteria (carditis, polyarthritis) and several minor criteria (fever, arthralgia, elevated ESR, leukocytosis, C-reactive protein, prolonged PR interval). Rheumatic fever is a sequela of untreated infection with Group A Streptococcus (S. pyogenes). S. pyogenes is differentiated from the other beta-hemolytic Strep by its sensitivity to the antibiotic bacitracin.
The catalase test (choice A) is used to differentiate Staphylococci from Streptococci. Staphylococci are catalase positive, Streptococci are catalase negative. So, S. pyogenes would be catalase negative.
The coagulase test (choice B) is used to differentiate Staph aureus from the other Staph spp. Staph aureus is coagulase positive; the others are negative.
Sensitivity to novobiocin (choice D) is used to differentiate Staph saprophyticus (resistant) from
Staph epidermidis (sensitive).
Sensitivity to optochin (choice E) is used to differentiate Strep pneumoniae (sensitive) from viridans Strep (resistant).
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