<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>: Organism Features Enterococcus faecalis Resistant to penicillins, aminoglycosides and sulfonamides. Intrinsic resistance to cephalosporins and cotrimoxazole. In co resistance -combine- Penicillin Aminoglycoside as they act synergestically. Staphylococcus aureus Rx : Parenteral therapy for serious infections Oral therapy for skin and soft tissue infections Sensitive to penicillin- DOC: Penicillin G Sensitive to methicillin-DOC: Nafcillin or oxacillin Resistant to methicillin MRSA- DOC: Vancomycin Sensitive to methicillin- DOC: Dicloxacillin, cephalexin Resistant to methicillin MRSA - DOC: Clindamycin Streptococcus pneumoniae Rx DOC- Penicillin G Alternative : Cephalosporinsceftriaxone Bacteroides fragilis Obligately anaerobe, non-spore forming gram-negative bacilli CF- Brain abscess, subdural empyema, epidural abscess, and meningitis Endocarditis, meningitis, septic ahritis and osteomyelitis Colonies- Brilliant red fluorescence Rx- Metronidazole 