Spontaneous bacterial peritonitis

See Peritoneal dialysis-associated peritonitis for PD peritonitis

Background

  • Develops in large, clinically obvious ascites secondary to cirrhosis
    • Portal hypertension → bowel edema → normal flora translocates across bowel wall into the peritoneum
  • 30% of ascitic patients will develop spontaneous bacterial peritonitis (SBP) in a given year

Causative Agents

Clinical Features

Differential Diagnosis

Diffuse Abdominal pain

Evaluation

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

Diagnosis of SBP via Ascitic Fluid Analysis

Standard Evaluation

  • Paracentesis results supporting a diagnosis of SBP:
    • Absolute neutrophil count (PMNs) ≥250, pH <7.35, OR blood-ascites pH gradient >0.1[1]
    • Bacteria on gram stain (single type)
    • SAAG > 1.1
      • Diagnostic of portal hypertension with 97% accuracy[2]
      • SBP rarely develops in patients without portal hypertension
    • Protein < 1, Glucose > 50 (otherwise concern for secondary bacterial peritonitis)

For bloody tap, subtract 1 WBC for every 250 RBC[3]

If on peritoneal dialysis

See Peritoneal dialysis-associated peritonitis

  • Cell count >100/mm with >50% neutrophils most consistent with infection[4]

Spontaneous versus secondary bacterial peritonitis

  • Importance of distinction
    • Mortality of secondary bacterial peritonitis (eg. perforated appendicitis, cholecystitis) ~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) with 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

Management

Antibiotics

Albumin

Reduces renal failure and hospital mortality if given within 6 hours[5]

  • 1.5gm/kg at diagnosis; 1gm/kg on day 3
  • Give for all or (larger effect) if creatinine >1mg/dL, BUN >30mg/dL, or T Bili >4mg/dL

Disposition

  • Most admitted
    • Can consider discharge with PO antibiotics if has mild, uncomplicated disease and close follow up

See Also

References

  1. Wilkerson R, Sinert, R. The Use of Paracentesis in the Assessment of the Patient With Ascites. Ann Emerg Med 2009, 54(3): 465-68.
  2. Runyon BA, Montano AA, Akriviadis EA, et al. The serum-ascites albumin gradient is superior to the exudate-transudate concept in the differential diagnosis of ascites. Ann Intern Med 1992; 117:215.
  3. Hoefs JC "Increase in ascites white blood cell and protein concentrations during diuresis in patients with chronic liver disease."Hepatology. 1981;1(3):249. PMID 7286905
  4. ISPD GUIDELINES/RECOMMENDATIONS http://www.ispd.org/guidelines/articles/update/ispdperitonitis.pdf
  5. Jamtgaard, et al. Does albumin infusion reduce renal impairment and mortality in patients with SBP. Annals of EM. April 2016. 67(4):458-458.