Spontaneous Bacterial Peritonitis (SBP)

Background

• Infection of ascitic fluid without evidence of obvious source of infection 
• Present in ~1/3 of hospitalized patients with cirrhosis HEPATOLOGY 237 
  • Presentation: fever, abdominal pain, encephalopathy, renal failure, acidosis +/- leukocytosis 
  • Up to 1/3 of patients may be asymptomatic or only have HE +/- AKI 
  • Pathogenesis: Translocation of bacteria through intestinal wall into bloodstream, lymphatics, extraintestinal sites

Evaluation

• Any admitted pt with cirrhosis + ascites should have diagnostic para (even in asymptomatic patients not suspected of SBP) (delaying para > 12h is associated with a 2.7-fold increase in mortality) 
  • Obtain cell count with diff, total protein, albumin (for SAAG) and culture 
  • Calculate PMNs: total nucleated cells x % neutrophils. 
  • PMN≥ 250 cell/mm3 = diagnostic of SBP; if > 100k RBCs -> correct by subtracting 1 PMN for every 250 RBCs
• SBP: PMN ≥ 250 ± positive culture. Culture negative SBP-> treat 
  • A positive ascitic bacterial culture + PMN < 250 = bacterascites; asymptomatic patients are generally not to receive antibiotics as it is likely a contaminant (however, this should be discussed with attending as some data suggest antibiotics may be helpful, regardless repeat paracentesis after 48h to exclude progression to SBP should be obtained)

Management of confirmed SBP

• Immediately start empiric antibiotics 
  • Most common pathogens: E. coli, Klebsiella, strep species, staph species 
  • Ceftriaxone 2g q24h for 5-7 days 
  • If recent hospital admission (within 90 days), recent exposure to BSA, SBP diagnosed > 48h of admission, or with sepsis -> zosyn +/- vanc (if prior infection or positive MRSA nares) or daptomycin (if hx of VRE infection) 
  • In patients with recent exposure to zosyn -> consider meropenem for MDR coverage 
• IV albumin 1.5g/kg on day 1 + 1g/kg on day 3 (max dose 100g) 
  • NSBB do not need to be discontinued unless hypotensive or AKI present; if stopped, reinitiation should be based on recovery of blood pressure 
  • PPI’s ↑ risk for SBP in pts with cirrhosis and should be reviewed for appropriateness 
  • Repeat diagnostic paracentesis ~48h after initiating antibiotics 
  • If < 25% total decrease in PMNs, broaden antibiotics

Prophylaxis

• Ceftriaxone 1g QD in patients with UGIB 
• Indications for lifelong prophylaxis: 
  • 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 is unlikely if SAAG < 1.1 g/dL 
• Ascitic leukocyte count of 5-10k -> consider secondary peritonitis 
• High ascitic amylase -> consider pancreatic ascites 
• High ascitic bilirubin -> consider bile leak or gallbladder perforation 
• Peritoneal fluid CEA and alkaline phosphatase -> consider hollow viscus injury 
• Evaluate with cross-sectional imaging and consult surgery as appropriate 
• Runyon’s Criteria, requires 2/3 criteria (protein, glucose, LDH):