Spontaneous bacterial peritonitis

Revision as of 21:27, 7 May 2016 by Rossdonaldson1 (talk | contribs) (Background)

See Peritoneal dialysis-associated peritonitis for PD peritonitis


  • 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


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


  • Albumin and SERUM albumin
  • LDH and SERUM LDH at same time
  • Amylase

Specific circumstances

  • TB smear and culture
  • Cytology
  • TG
  • Billirubin

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




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 Cr >1 mg/dL, BUN >30 mg/dL, or T Bili >4 mg/dL


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

See Also


  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.