Skip to Main Content
Home Books Quick Medical Diagnosis & Treatment 2021

Anaerobic Infections, Intra-Abdominal

For further information, see CMDT Part 33-31: Anaerobic Infections

Key Features

  • 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

  • Related to infected organ

Diagnosis

  • Examination, laboratory tests, cultures, and CT scan

Treatment

  • 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 33–6.Treatment of anaerobic intra-abdominal infections.
View Table|Favorite 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

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.

This site uses cookies to provide, maintain and improve your experience. MHE Privacy Center Close