This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Which of the following organism, when isolated in the blood, requires the synergistic activity of penicillin + amino glycoside for appropriate therapy : 
Select and explain. 
A. Enterococcus faecalis, B. Staph. aureus, C. Streptococcus pneumoniae, D. Bacteriodes fragilis
A: Enterococcus faecalis
Answer: A: Enterococcus faecalis 
Explanation: See the following line.
“Unlike streptococci, enterococci are not reliably killed by penicillin or ampicillin alone. Because in vitro testing has shown evidence of synergistic killing by combination of penicillin or ampicillin with an amminoglycoside, combined therapy is recommended for enterococcal endocarditis and meningitis.”

Enterococci are resistant to all cephalosporins