Peritonitis, Bacterial

SOURCE

Source: Gross AW, Olsen KM, DiPiro JT. Intra-abdominal infections. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=146072317. Accessed April 14, 2017.

CONDITION/DISORDER SYNONYMS

• Intra-abdominal infection.

• Spontaneous bacterial peritonitis.

DEFINITION

• Acute, inflammatory response of peritoneal lining to microorganisms, chemicals, irradiation, or foreign body injury.

  • Primary peritonitis: intra-abdominal focus may not be evident.

  • Secondary peritonitis: focal disease process evident.

  • Abscess: purulent collection of fluid separated from surrounding tissue by wall consisting of inflammatory cells and adjacent organs.

    • Usually contains necrotic debris, bacteria, and inflammatory cells.

ETIOLOGY

• Table 1 summarizes many potential causes of bacterial peritonitis.

• Causes of intra-abdominal abscess overlap those of peritonitis.

  • May occur sequentially or simultaneously.

  • Appendicitis most frequent cause of abscess.

• Primary peritonitis most commonly associated with end-stage alcoholic cirrhosis.

PATHOPHYSIOLOGY

• Peritonitis.

  • Primary peritonitis.

    • Bacteria enter abdomen:

      • Via bloodstream or lymphatic system.

      • By transmigration through bowel wall.

      • Through indwelling peritoneal dialysis (PD) catheter.

      • Via fallopian tubes.

  • Secondary peritonitis.

    • Bacteria enter peritoneum or retroperitoneum as result of disruption of integrity of gastrointestinal (GI) tract caused by diseases or traumatic injuries.

    • Focal disease process.

  • Inflammatory process within peritoneum involves peritoneal lining.

    • Fluid and protein shift into abdomen (called “third spacing”)

    • May cause hypotension, hypovolemic shock, and death.

• Abscess.

  • Forms through combined action of:

    • Inflammatory cells (eg, neutrophils)

    • Bacteria.

    • Fibrin.

    • Other inflammatory mediators.

  • Oxygen tension low within abscess, allowing anaerobic bacteria to thrive.

EPIDEMIOLOGY

• Primary peritonitis often caused by single organism.

  • Most commonly associated with end-stage alcoholic cirrhosis and with Escherichia coli

  • In children, pathogen usually group A Streptococcus, Streptococcus pneumoniae, E. coli, or Bacteroides species.

  • With PD, infection most often caused by common skin organisms: Staphylococcus epidermidis, Staphylococcus aureus, streptococci, and enterococci.

• Secondary peritonitis most often polymicrobial (Table 2)