Treatment

Principal of treatment of most anaerobically caused infections is drainage of an abscess (when present), plus antibiotics. The choice of antibiotic(s) must include coverage for both aerobes and B. fragilis.

Antibiotics Of all anaerobes, Bacteroides group are the most resistant to antibiotics, while oral anaerobes are the most sensitive.

• B. fragilis group - uniformly resistant to penicillin
  Susceptible to: Metronidazole (100%) Ampicillin + Sulbactam (96%), Ticarcillin/Clavulanic acid (98%) Imipenem (98%), Cefoxitin (90%), Cefotetan (80%), Clindamycin (80-85%), Ceftizoxime (80%), Chloramphenicol (100%), Piperacillin (80%).
  Not susceptible to: Ampicillin, oxacillin, 1st generation cephalosporins, other 3rd generation cephaloporins, quinolones, tetracycline, and sulfa based antibiotics.
• P. bivia, P. disiens
  Similar to B. fragilis, but overall more susceptible - not penicillin.
• P. melanogenic, P. gingivola, P. oralis
  May be susceptible to penicillin and most antibiotics listed above.
• Fusobacterium - penicillin sensitive, although occasional resistance has been reported