Definition

Acute inflammation of diverticula (sac-like protrusions of the wall of the colon) that can cause severe abdominal pain

Classification based on complexity:

• Uncomplicated: No involvement of peritoneal cavity and no abscess
• Complicated: Involvement of the peritoneal cavity and/or abscess

Classification based on severity:

• Mild: Not critically ill with no signs of sepsis or septic shock

• Severe: Critically ill with signs of sepsis or septic shock

Most Likely Pathogens

Bacteria:

• Enterobacterales (mostly Escherichia coli including multidrug- resistant strains)
• Streptococcus spp. (e.g. of the S. anginosus group)
• Enterococcus spp.

• Anaerobes (mostly Bacteroides spp.)
Fungi (consider if recent course of antibiotics):

• Mostly Candida albicans
Parasites (consider in endemic settings):

• Enterobius vermicularis (pinworm)

Clinical Presentation

• Acute pain in the left or right lower abdominal quadrants with chills, nausea and vomiting; fever (≥ 38.0 °C) may be absent

• Left diverticulitis is more common in Europe and North America, right diverticulitis in Asia

Important:

Important:

• Consider peritonitis if severe pain, diffuse rebound tenderness upon sudden release of pressure on the abdomen and abdominal muscular tensing

• Hypotension and signs of organ hypoperfusion (e.g. reduced urine output) are potential signs of sepsis /septic shock that need urgent treatment

Microbiology Tests

Mild cases: Not usually needed

Severe cases:
• Blood cultures (ideally before starting antibiotics)
• Microscopy and culture of abscess øuid material (if this can be drained) to adjust empiric antibiotic treatment

Other Laboratory Tests

• Determine disease severity and help identify a bacterial infection: White blood cell count, C-reactive protein and/or procalcitonin

• If sepsis is suspected consider additional laboratory tests.

Imaging

Abdominal ultrasound or CT of the abdomen (depending on availability) to conörm the diagnosis

Treatment

Antibiotic Treatment Duration

• Most mild cases do not need antibiotic treatment • Treatment with antibiotics alone: 4 days (if good

clinical recovery and symptoms resolved)

• Treatment with antibiotics & surgical source control: Stop 4 days after adequate source control (surgery) is achieved otherwise, continue until clinically stable and afebrile

Mild cases

Most mild cases do not need antibiotic treatment

All dosages are for normal renal function

Antibiotics are listed in alphabetical order and should be considered equal treatment options unless otherwise indicated

First Choice

Second Choice

Metronidazole has excellent oral bioavailability and the IV route should be reserved for patients with impaired gastrointestinal function

Severe Cases

All dosages are for normal renal function

Antibiotics are listed in alphabetical order and should be considered equal treatment options unless otherwise indicated

First Choice

Second Choice

Consider meropenem only in complicated cases if there is a high risk of infection with ESBL-producing Enterobacterales

Clinical Considerations

• Uncomplicated cases in immunocompetent patients: antibiotics not needed if there are no systemic signs of infection; if these cases do not resolve spontaneously after 2-3 days, consider antibiotics

• Uncomplicated cases in severely immunocompromised patients: treat with antibiotics alone (if close follow up possible)

• Complicated cases: treat with antibiotics and surgical source control (e.g. drainage of large abscesses >5 cm or colonic resection)

Empiric antibiotic treatment should be guided by: The severity of symptoms, considering local prevalence of resistance (particularly of isolates of Enterobacterales producing ESBL) and individual risk factors for resistant pathogens

Important:

• Simplify empiric treatment to a more narrow- spectrum antibiotic based on culture results or rapid clinical improvement if culture results unavailable

• Step down to oral treatment is based on improvement of symptoms, signs of infection and the ability to take oral antibiotics

• If signs and symptoms persist, abdominal imaging is suggested, or an alternative extra-abdominal source of infection should be considered

References

Web Annex. Infographics. In: The WHO AWaRe (Access, Watch, Reserve) antibiotic book. Geneva: World Health Organization; 2022 (WHO/MHP/HPS/EML/2022.02). Licence: CC BY-NC-SA 3.0 IGO.