What are the initial treatment steps in managing severe intraabdominal infection?

Initial Treatment Steps for Severe Intra-abdominal Infection

The initial management of severe intra-abdominal infection requires rapid fluid resuscitation, early antimicrobial therapy, and prompt source control through surgical or percutaneous intervention, with the timing and approach determined by the patient's hemodynamic status and extent of peritonitis. 1

Initial Assessment and Resuscitation

• Routine history, physical examination, and laboratory studies will identify most patients with suspected intra-abdominal infection requiring further management 1
• Rapid restoration of intravascular volume should be initiated immediately, especially in patients with septic shock 1
• For patients without evidence of volume depletion, intravenous fluid therapy should begin when intra-abdominal infection is first suspected 1
• CT scan is the imaging modality of choice for patients not undergoing immediate laparotomy to determine the presence and source of infection 1
• Further diagnostic imaging is unnecessary in patients with obvious signs of diffuse peritonitis who require immediate surgical intervention 1

Antimicrobial Therapy

• Antimicrobial therapy should be initiated once intra-abdominal infection is diagnosed or considered likely 1
• For patients with septic shock, antibiotics should be administered as soon as possible to reduce mortality 1, 2
• For patients without septic shock, antimicrobial therapy should be started in the emergency department 1
• Empiric antimicrobial therapy should be active against enteric gram-negative aerobic and facultative bacilli, enteric gram-positive streptococci, and obligate anaerobes 1, 3
• For community-acquired infections of mild-to-moderate severity, appropriate regimens include:
  • Single agents: cefoxitin, ertapenem, moxifloxacin, tigecycline, or ticarcillin-clavulanic acid 1
  • Combination therapy: cefazolin, cefuroxime, ceftriaxone, cefotaxime, ciprofloxacin, or levofloxacin, each combined with metronidazole 1
• For severe infections or high-risk patients, broader spectrum agents are recommended:
  • Single agents: imipenem-cilastatin, meropenem, doripenem, or piperacillin-tazobactam 1, 4
  • Combination therapy: cefepime, ceftazidime, ciprofloxacin, or levofloxacin, each combined with metronidazole 1
• Satisfactory antimicrobial drug levels should be maintained during source control intervention, which may necessitate additional administration just before the procedure 1

Source Control

• An appropriate source control procedure is recommended for nearly all patients with intra-abdominal infection 1
• Patients with diffuse peritonitis should undergo emergency surgical procedure as soon as possible, even if ongoing measures to restore physiologic stability need to be continued during the procedure 1, 2
• Where feasible, percutaneous drainage of abscesses and other well-localized fluid collections is preferable to surgical drainage 1
• For hemodynamically stable patients without evidence of acute organ failure, intervention may be delayed for up to 24 hours if appropriate antimicrobial therapy is given and careful clinical monitoring is provided 1
• The goals of source control are to drain infected foci, control ongoing peritoneal contamination by diversion or resection, and restore anatomic and physiological function 1, 5

Special Considerations

• In patients with severe peritonitis, mandatory or scheduled relaparotomy is not recommended in the absence of intestinal discontinuity, abdominal fascial loss, or intra-abdominal hypertension 1
• Highly selected patients with minimal physiological derangement and well-circumscribed infection focus may be treated with antimicrobial therapy alone without source control, provided close clinical follow-up is possible 1
• Clinical factors predicting failure of source control include delay in initial intervention (>24h), high severity of illness (APACHE II score >15), advanced age, comorbidities, low albumin level, and diffuse peritonitis 1
• Blood cultures do not provide additional clinically relevant information for patients with community-acquired intra-abdominal infection and are not routinely recommended 1

Duration of Therapy

• Antimicrobial therapy for established infection should generally be limited to 4-7 days, unless source control is difficult to achieve 1
• For immunocompetent and non-critically ill patients with adequate source control, 4 days of antibiotic therapy is sufficient 1
• For immunocompromised or critically ill patients with adequate source control, antibiotic therapy up to 7 days based on clinical conditions and inflammation indices is recommended 1
• Patients with ongoing signs of infection beyond 7 days warrant further diagnostic investigation 1