What are the latest treatment recommendations for infectious diseases according to the Infectious Diseases Society of America (IDSA) 2024 guidelines?

IDSA 2024 Guidelines on Complicated Intra-Abdominal Infections

Blood Cultures

In patients with suspected intra-abdominal infections who have fever AND hypotension, tachypnea, or delirium, OR concern for antibiotic-resistant organisms, obtain blood cultures. 1

When to Obtain Blood Cultures:

• Obtain blood cultures if the patient has:

  • Elevated temperature PLUS any of: hypotension, tachypnea, or delirium 1
  • Concern for antibiotic-resistant organisms that would change treatment 1

• Concern for resistant organisms includes: 1

  • High regional resistance rates to empiric agents
  • Prior colonization/infection with resistant organisms within 90 days
  • Antibiotic use within 90 days
  • Elderly or immunocompromised status
  • Healthcare-associated infection
  • Concern for ascending cholangitis or complex abscess 1

• Do NOT routinely obtain blood cultures if: 1

  • Normal or elevated temperature WITHOUT hypotension, tachypnea, or delirium
  • No concern for resistant organisms
  • Non-immunocompromised patient

Diagnostic Imaging

Acute Cholecystitis/Cholangitis:

Start with abdominal ultrasound as the initial imaging modality in non-pregnant adults. 1

• If ultrasound is equivocal and clinical suspicion persists, obtain CT with IV contrast 1
• If both ultrasound and CT are non-diagnostic for cholecystitis, obtain MRI/MRCP or HIDA scan 1
• For pregnant patients, either ultrasound or MRI can be considered (no clear preference established) 1

Acute Diverticulitis:

Obtain abdominal CT with IV contrast as the initial imaging modality in non-pregnant adults. 1

• If CT is unavailable or contraindicated, obtain ultrasound or MRI 1
• For pregnant patients, either ultrasound or MRI can be considered (no clear preference established) 1

Intra-Abdominal Abscess:

CT or ultrasound are both reasonable initial imaging options, with choice depending on clinical context and availability. 1

• Ultrasound has dual utility for diagnosis and guiding percutaneous drainage 1
• CT with IV contrast improves visualization of abscess walls 1
• In children, ultrasound is preferred to avoid radiation exposure 1

Intra-Abdominal Fluid Cultures

Obtain intra-abdominal cultures during source control procedures in patients with complicated intra-abdominal infections. 1

When to Obtain Cultures:

• Obtain cultures if: 1

  • Patient has complicated intra-abdominal infection requiring source control procedure
  • Patient is immunocompromised (increased risk for resistant organisms)
  • Complicated disease is recognized at time of surgery

• Do NOT routinely obtain cultures if: 1

  • Uncomplicated appendicitis in immunocompetent patients undergoing appendectomy

Collection Method:

• Fluid inoculation into blood culture bottles is the preferred collection method 1
• Avoid using swabs for specimen collection (suboptimal organism yield) 1
• If Gram stain is needed, collect additional specimen before inoculating blood culture bottle 1

Risk Stratification

Use APACHE II score for risk stratification within 24 hours of hospitalization or ICU admission in adults with complicated intra-abdominal infections. 1

• APACHE II is the preferred severity of illness score for predicting 30-day or in-hospital mortality 1
• Risk stratification is important for guiding management decisions 1

Key Implementation Points

• Treatment should be initiated as soon as possible after diagnosis 1
• All recommendations are conditional with very low to moderate certainty of evidence, reflecting the limited high-quality data available 1
• Clinical judgment remains essential, and consultation with infectious diseases specialists is recommended for complex cases 1