Spontaneous bacterial peritonitis

See Peritoneal dialysis-associated peritonitis for PD peritonitis

Background

• Abreviation: SBP
• Develops in large, clinically obvious ascites 2/2 cirrhosis
  • Normal flora translocate across the bowel wall into the peritoneum
• 30% of ascitic pts will develop SBP in a given year
• There is no platelet count or INR that is a contraindication to paracentesis

Clinical Features

• Fever (70%)
• Abdominal pain (diffuse) (60%)
• Altered mental status (55%)
• ~15% of patients have no signs/symptoms

Differential Diagnosis

• Peritoneal dialysis-associated peritonitis

Diffuse Abdominal pain

• Abdominal aortic aneurysm
  • Aortocaval fistula
• Acute gastroenteritis
• Aortoenteric fisulta
• Appendicitis (early)
• Bowel obstruction
  • Large bowel obstruction
    • Ogilvie's syndrome
  • Small bowel obstruction
  • Malignant bowel obstruction
• Bowel perforation
• Gastroparesis
• Diabetic ketoacidosis
• Hernia
• Inflammatory bowel disease
• Mesenteric ischemia
• Pancreatitis
• Peritonitis
• Sickle cell crisis
• Spontaneous bacterial peritonitis
• Volvulus

Diagnosis

Consider alternative diagnoses at the same time

SBP Work-Up of Ascitic Fluid via Paracentesis

• Cell count with differential
• Gram stain
• Culture (10cc in blood culture bottle)
• Glucose
• Protein

Fluid Analysis

• Paracentesis results supporting a diagnosis of SBP:
  • Total WBC >500
  • Absolute neutrophil count > 250
  • Bacteria on gram stain (single type)
  • SAAG > 1.1
  • Protein < 1, Glucose > 50 (otherwise concern for secondary bacterial peritonitis)

Spontaneous versus secondary bacterial peritonitis

• Importance of distinction
  • Mortality of secondary bacterial peritonitis ~100% if treatment is only antibiotics without surgery
  • Mortality of unnecessary surgery in patients with SBP ~80%
• Laboratory findings
  • Secondary bacterial peritonitis strongly suggested by:
    • Neutrocytic fluid (PMN ≥250) w/ two or more of the following:
      • Total protein concentration >1 g/dL (10 g/L)
      • Glucose concentration <50 mg/dL (2.8 mmol/L)
      • LDH greater than upper limit of normal for serum
    • Ascitic alk phos >240
    • Gram stain
      • Large numbers of different bacterial forms
• Imaging
  • If evidence of secondary bacterial peritonitis obtain abdominal imaging
    • If no evidence of free air or contrast extravasation then surgery is not indicated

Treatment

Antibiotics

• SBP
  • Broad-spectrum covering enterobacter (63%), pneumococcus (15%), entercocci (10%)
  • Anaerobes causative agent <1%
    • 3rd-generation cephalosporin is agent of choice:
      • Cefotaxime 2g IV q8hr or Ceftriaxone 1-2g IV q12-24hr
    • If beta-lactam allergy consider ciprofloxacin 400mg IV q12hr
• Secondary bacterial peritonitis
  • 3rd-generation cephalosporin + metronidazole
  • Surgery

Albumin

• Reduces renal failure and hospital mortality
• 1.5gm/kg at diagnosis; 1gm/kg on day 3

Disposition

• Can consider discharge w/ PO abx if pt has mild, uncomplicated disease and close f/u

See Also

• Paracentesis
• Peritoneal dialysis-associated peritonitis

References

• Paracentesis. N Engl J Med 2006; 355