Which of the following organisms, when isolated in the blood, requires the synergistic activity of penicillin plus an aminoglycoside for appropriate therapy -: (A) Enterococcus faecalis, (B) Staphylococcus aureus, (C) Str. pneumoniae, (D) Bacteroides fragilis
Answer is A. Organism Features Enterococcus faecalis Resistant to penicillins, aminoglycosides and sulfonamides. Intrinsic resistance to cephalosporins and cotrimoxazole. In c/o 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 : Cephalosporins(ceftriaxone) Bacteroides fragilis Obligately anaerobe, non-spore forming gram-negative bacilli C/F- Brain abscess, subdural empyema, epidural abscess, and meningitis Endocarditis, meningitis, septic ahritis and osteomyelitis Colonies- Brilliant red fluorescence Rx- Metronidazole