<prompt> Which of the following organisms, when isolated in the blood, requires the synergistic activity of penicillin plus an aminoglycoside for appropriate therapy-Enterococcus faecalisStaphylococcus aureusStr. pneumoniaeBacteroides fragilis  <response>: Ans. is a i.e., Enterococcus faecalis Unlike streptococci, enterococci are not reliably killed by penicillin or ampicillin alone. Because of synergistic action of Penicillin and aminoglycoside against enterococci combination therapy is recommended . 