Secondary Peritonitis

Infection of the peritoneal cavity due to spillage of organisms from, usually, the gastrointestinal or genitourinary tract (e.g. due to perforation, trauma, inflammatory disease)

Diagnostic Pearls

Prompt abdominal and pelvic CT to identify source

Surgical/gastroenterology consultation for source control, (debridement, percutaneous drainage), which is the cornerstone of therapy

Blood cultures in severely ill and health care associated complicated infections; peritoneal cultures can help define microbiology

Procalcitonin (PCT) not usually useful

Empiric Therapy

Check one:

Mild-moderate

Those who do not meet criteria for severe infection but may have:

SIRS (two or more of: Temperature >38°C or <36°C; Heart rate >90/min; Respiratory rate >20/min; White blood cell count >12,000/mm3 or <4,000mm3)
Co-morbidities (e.g. diabetes, advanced age)
Significant pain

Severe

Requiring ICU admission, or

Sepsis (life-threatening organ dysfunction e.g. hypotension, acute renal failure, caused by dysregulated host response to infection)

Check one:

Community acquired

Acquired in the outpatient setting

Health care-associated

Acquired more than 48 hours post admission, or

Hospitalization, surgery, regular outpatient visits (e.g. dialysis, chemotherapy) within last 90 days or residing in long term care

Source-based Empiric Therapy

Microbiology

Usual Organisms (can be polymicrobial)

Enterobacteriaceae (E. coli, Klebsiella)

Less Common Organisms

Enteric anaerobes (B. fragilis, Clostridium spp.)

Streptococci

Enterococcus faecalis

Organisms of Interest in IAI