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Spontaneous Bacterial Peritonitis (SBP)

Patricia Checinski


  • Infection of ascitic fluid without evidence of a surgical intra-abdominal source

  • Presentation: fever, abdominal pain, encephalopathy, renal failure, acidosis, and/or leukocytosis


  • Any pt with cirrhosis and ascites who is admitted should have diagnostic paracentesis to rule out SBP. Delaying paracentesis > 12 hours is associated with a 2.7-fold increase in mortality.

  • Obtain cell count with diff.

    • Calculate the PMNs: total nucleated cells x % neutrophils.
    • PMNs > 250 cells is diagnostic of SBP. If there are greater than 100k RBCs, you should correct for them: for every 250 RBCs, subtract 1 PMN
  • A positive ascitic bacterial culture with PMN <250 is called bacterascites and asymptomatic patients should NOT receive antibiotics. You will also frequently see culture-negative SBP (neutrocytic ascites) which SHOULD be treated (see below).


  • Immediately start empiric antibiotics

  • Guidelines recommend cefotaxime IV 2gm q8 hours x 5 days, but we commonly use ceftriaxone IV 2g q24h for 5-7 days at VUMC and Nashville VA.

    • Most common culprits (E. coli, Klebsiella, streptococcal species, staphylococcal species)
    • If SBP developed with recent hospital admission (90 days), recent exposure to BSA, diagnosed >48 hours of admission, or with sepsis, consider zosyn or meropenem to cover MDROs
  • IV albumin 1.5 g/kg on day 1 and 1g/kg on day 3

  • Discontinue beta-blockers once SBP develops and do not restart until SBP is completely treated, Na >130, and no AKI

  • PPI’s ↑ risk for SBP in pts with cirrhosis, and should be reviewed for appropriateness

  • Repeat diagnostic paracentesis two days after antibiotics initiated

    • If <25% decrease in PMNs, antibiotics should be broadened and consider secondary bacterial peritonitis


  • GI bleed: ceftriaxone 1g daily ciprofloxacin 500mg BID (preferred) or Bactrim one DS tablet BID x 5-7 days

  • Outpatient lifelong ppx, indications:

    • Prior SBP
    • Ascitic protein <1.5 AND
      • Child Pugh >9 and bilirubin >3 OR
      • Renal dysfunction (Cr >1.2, Na <130, or BUN >25)
    • Preferred: Bactrim DS tab daily or ciprofloxacin 500mg daily
    • Alternatives: cefdinir 300mg daily, Augmentin 875/125 daily

If suspicion is high for secondary bacterial peritonitis:

  • Examine serum-ascites albumin gradient (SAAG). SBP develops in pts with portal hypertension, defined by SAAG > 1.1 g/dL. SBP is unlikely if SAAG is < 1.1 g/dL.

  • While not particularly sensitive, an ascitic leukocyte count of 5-10k should prompt consideration of secondary peritonitis

  • Amylase from fluid can also be helpful to point towards pancreatic ascites, while bilirubin can indicate gallbladder perforation. Peritoneal fluid CEA and alkaline phosphatase can additionally help identify hollow viscus injury.

  • Evaluate with cross-sectional imaging and surgical consultation as appropriate

  • Runyon’s Criteria to distinguish, requires ⅔ criteria below (protein, glucose, LDH)

Spontaneous Secondary
Protein (g/dL) <1 >1
Glucose (mg/dL) ≥50 <50
LDH (U) Elevated, but < 225 >225
Organisms 0-1 Polymicrobial

Last update: 2022-11-03 23:30:52