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.

TABLE 1.Causes of Bacterial Peritonitis

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TABLE 1. Causes of Bacterial Peritonitis

Primary bacterial peritonitis

Peritoneal dialysis

Cirrhosis with ascites

Nephrotic syndrome

Secondary bacterial peritonitis

Miscellaneous causes

Diverticulitis

Appendicitis

Inflammatory bowel diseases

Salpingitis

Biliary tract infections

Necrotizing pancreatitis

Neoplasms

Intestinal obstruction

Perforation

Mechanical GI problems

Any cause of small bowel obstruction (adhesions and hernia)

Vascular causes

Mesenteric arterial or venous occlusion (atrial fibrillation)

Mesenteric ischemia without occlusion

Trauma

Blunt abdominal trauma with rupture of intestine

Penetrating abdominal trauma

Iatrogenic intestinal perforation (endoscopy)

Intraoperative events.

Solid organ transplant in the abdomen.

Peritoneal contamination during abdominal operation

Leakage from GI anastomosis

GI, gastrointestinal.

Reprinted with permission from Wells BG, DiPiro JT, Schwinghammer TL, et al. Pharmacotherapy Handbook. 10th ed. New York, NY: McGraw-Hill; 2017.

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)