Managing Intra-Abdominal Infections in the ICU

Managing Intra-Abdominal Infections in the ICU


Patient CM, an elderly male with colon cancer, had a bowel resection surgery. Post-operatively he gradually deteriorated. Today he was febrile, had severe abdominal pain, his white count was elevated and he looked very sick. CM went back to the OR for a wash-out and repair of an anastomotic leak. He is now in the ICU. CM has secondary peritonitis. Secondary peritonitis, is defined as spillage
of normal gut flora into the peritoneum. Intra-abdominal infections are categorized by the extent,
– localized or extending beyond the initial site of infection: localized peritonitis with abscess
formation, or diffuse peritonitis; onset — community or hospital; and severity of infection. Severe disease can involve comorbidities, shock, immunosuppression, older age, an APACHE II score of more than 15, and organ dysfunction. Clinical presentation of secondary peritonitis includes abdominal pain with rigidity or ‘guarding’, nausea, vomiting, diarrhea or constipation, fever, chills, and rigors. Imaging studies are useful to visualize sites of infection. Community acquired peritonitis is caused by
normal gut flora. In hospital-acquired peritonitis also consider difficult-to-treat nosocomial organisms. Cultures are only recommended in hospital
acquired infections or severely ill patients as gut flora are relatively predictable. Empiric therapy should cover core pathogens, and account for severity of infection, local resistance patterns, prior antibiotic exposure
and possible resistant organisms. Anti-enterococcal antibiotics in mild to moderate community
acquired infections don’t alter outcomes. In severe infections, empiric therapy should
include anti-enterococcal activity, particularly for patients with prior exposure to broad-spectrum antibiotics, liver transplant patients, and patients with valvular heart disease and prosthetic devices. For CM, a broad spectrum antibiotic such
as piperacillin-tazobactam is reasonable. If difficult to treat or problem bugs are
not found in cultures, narrow the antimicrobial coverage. Regardless of antibiotics, adequate source
control, such as abscess drainage or intrabdominal washout, is crucial to resolution of infection.
Once source control is achieved duration of antibiotics is guided by infection complexity
For uncomplicated community-acquired intra-abdominal infections such as non-perforated appendicitis, only surgical prophylaxis is needed. Complicated infections require 4-7 days of therapy if
the patient is stable and improving. Conversely, for a patient who does not improve, rather
than prolonging the course of antibiotics, re-assess for source control. Key messages: target therapy to normal gut
flora, consider risk factors for problem bugs, duration of therapy is typically 4 — 7 days
after achieving source control, clinical deterioration warrants further investigation rather than
more antibiotics.

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