A patient, suspected to have bacterial endocarditis, had two sets of blood cultures drawn. All four bottles are positive with gram-positive cocci in pairs and chains.
On sheep blood agar, the gray, transparent, alpha-hemolytic colonies are catalase negative, optochin resistant, ESC negative and PYR negative. Which of the following patient histories correlates with the presence of this organism?
A) 78-year-old male with bacterial pneumonia
B) 3-day-old premature male
C) 47-year-old female with a heart murmur and a history of dental surgery
D) 16-year-old female with a history of untreated pharyngitis
Question 2
A blood culture yields yellow-pigmented, beta-hemolytic, catalase-positive, gram-positive cocci in clusters. The department is out of Staphylococcus latex agglutination reagent. The microbiologist sets up a tube coagulase and mannitol salt agar.
She incubates both at 35C in CO2 overnight. The next day the coagulase test is negative and the mannitol salt agar displays yellow colonies. How will you proceed with these results?
A) Report this organism as Staphylococcus not S. aureus
B) Repeat the tests due to invalid results
C) Test the organism for novobiocin resistance
D) Report this organism as Staphylococcus aureus
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