Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 33-31: Anaerobic Infections + Key Features Download Section PDF Listen +++ ++ Each gram of stool contains up to 1011 anaerobes, predominantly Bacteroides fragilis Clostridia Peptostreptococci These organisms play a central role in most intra-abdominal abscesses following trauma to the colon as well as Diverticulitis Appendicitis Perirectal abscess Hepatic abscess Cholecystitis The bacteriology of these infections includes anaerobes as well as enteric gram-negative rods and, on occasion, enterococci + Clinical Findings Download Section PDF Listen +++ ++ Related to infected organ + Diagnosis Download Section PDF Listen +++ ++ Examination, laboratory tests, cultures, and CT scan + Treatment Download Section PDF Listen +++ ++ Therapy should be directed both against anaerobes and gram-negative aerobes Antibiotics that are reliably active against B fragilis include Metronidazole Moxifloxacin Tigecycline Chloramphenicol Carbapenems (ertapenem, imipenem, doripenem) Ampicillin-sulbactam Ticarcillin-clavulanic acid Piperacillin-tazobactam Ceftolozane/tazobactam Table 33–6 summarizes the antibiotic regimens for management of Moderate to moderately severe infections (eg, patient hemodynamically stable, good surgical drainage possible or established, low APACHE score, no multiple-organ failure) Severe infections (eg, major peritoneal soilage, large or multiple abscesses, patient hemodynamically unstable), particularly if drug-resistant organisms are suspected ++Table Graphic Jump LocationTable 33–6.Treatment of anaerobic intra-abdominal infections.View Table||Download (.pdf) Table 33–6. Treatment of anaerobic intra-abdominal infections. Community-onset Oral therapy Moxifloxacin 400 mg every 24 hours Intravenous therapy Moderate to moderately severe infections: Ertapenem 1 g intravenously every 24 hours or Ceftriaxone 1 g intravenously every 24 hours plus metronidazole intravenously or orally, 500 mg every 8 hours. If penicillin allergic, can replace ceftriaxone with ciprofloxacin 400 mg intravenously (or 500 mg orally) every 12 hours. Severe infections: Imipenem 0.5 g intravenously every 6–8 hours or meropenem 1 g every 8 hours or doripenem 0.5 g every 8 hours or piperacillin/tazobactam 3.75 g every 6 hours Health care–associated Intravenous therapy Imipenem 0.5 g intravenously every 6–8 hours or meropenem 1 g every 8 hours or doripenem 0.5 g every 8 hours or piperacillin/tazobactam 4.5 g every 6 hours or Ceftazidime or cefepime 2 g intravenously every 8 hours plus metronidazole 500 mg intravenously or orally every 8 hours