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For further information, see CMDT Part 33-31: Anaerobic Infections
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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
Diverticulitis
Appendicitis
Perirectal abscess
They may also participate in hepatic abscess and cholecystitis
The bacteriology of these infections includes anaerobes as well as enteric gram-negative rods and, on occasion, enterococci
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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
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
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