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Spontaneous Bacterial Peritonitis

Abdominal/Pelvic

Source: IDMP View on spectrum chart →
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1. Clinical Syndrome

Infection of ascitic fluid in cirrhotic patient without an evident intra-abdominal source. Diagnostic criterion: ascitic fluid PMN ≥250/mm³ on paracentesis (regardless of culture result).

Variants:

  • Culture-positive SBP — PMN ≥250 + positive ascitic culture (typically monomicrobial).
  • Culture-negative neutrocytic ascites (CNNA) — PMN ≥250 + negative culture. Treat as SBP.
  • Monomicrobial non-neutrocytic bacterascites (MNB) — PMN <250 + positive culture. Treat if symptomatic; observe + repeat para if asymptomatic.

Excludes: secondary peritonitis (perforated viscus, abscess) — polymicrobial, often anaerobes, total protein >1 g/dL, glucose <50, LDH > serum upper limit. Requires imaging + surgical/IR evaluation, broader empirics (covered by complicated-intra-abdominal-infection syndrome).

2. Pathogens

Consider the patient: Cirrhosis severity (Child-Pugh, MELD), prior SBP, prior abx prophylaxis (cipro, TMP-SMX), recent hospitalization or healthcare exposure (MDRO risk → higher MRSA/Pseudo/ESBL/VRE/Candida rates), nosocomial onset (>48 h after admission).

Consider the case: Community-acquired (E. coli / Klebsiella / pneumococcus dominate, narrow regimen ok) vs healthcare-associated (broader regimen mandatory). Concurrent GI bleed (raises SBP risk dramatically — prophylaxis indicated). Renal dysfunction at presentation (hepatorenal risk → albumin essential).

Common

Less common

3. Empiric Therapy

TierFirst choiceAlternativesDurationComments
Outpatient
  • 500 mg · PO daily · PO · Indefinite — prophylaxis
  • 1 DS tablet · daily · PO

    Alternative prophylaxis; useful if FQ resistance rising.

Indefinite secondary prophylaxis after first episode; 7 days during GI bleed**Prophylaxis only — not for active SBP.** Indications: prior SBP (lifelong secondary prophylaxis), acute GI bleed (ceftriaxone × 7 d preferred, then transition), advanced cirrhosis + low-protein ascites (<1.5 g/dL) + renal dysfunction or hepatic decompensation (AASLD 2021 primary prophylaxis).
Admitted to ward
  • 2 g · q24h · IV · 5 days
  • 875 mg · PO BID · PO

    Oral step-down if afebrile, eating, hemodynamically stable by day 2 — selected community-acquired cases.

5 days (community-acquired, uncomplicated)**Community-acquired SBP, no prior healthcare exposure.** Ceftriaxone covers E. coli, Klebsiella, pneumococcus, most strep. **Add IV albumin 1.5 g/kg day 1 + 1 g/kg day 3** if Cr >1, BUN >30, or bili >4 — reduces hepatorenal syndrome and mortality (Sort 1999 NEJM).
Admitted to ICU
  • 4.5 g · q6h (extended infusion) · IV · 5–7 days
  • 1 g · q8h · IV

    If high local ESBL prevalence, prior ESBL isolate, or carbapenem-sparing not feasible.

  • Meropenem + daptomycin 1 g q8h + 6 mg/kg q24h · — · IV

    **Healthcare-associated SBP + septic shock** — covers carbapenem-resistant GNR risk + VRE/MRSA. Step down on cultures.

5–7 days, longer if bacteremia**Healthcare-associated / nosocomial SBP** (prior hospitalization, prior abx exposure within 90 days, nosocomial onset). MDRO rates of 20–40% in this group — empiric cephalosporin failure rate too high. Continue albumin. Discuss with ID.

Add coverage if:

MRSA coverage
  • Known MRSA colonization
  • Healthcare-associated SBP
  • Septic shock with healthcare exposure

Add:

  • load + AUC-guided · — · IV
Pseudomonas coverage
  • Healthcare-associated
  • Recent broad-spectrum abx
  • Septic shock

Add:

  • 4.5 g · q6h · IV

    Replaces ceftriaxone.

ESBL coverage
  • Prior ESBL isolate
  • Healthcare-associated with severity
  • Broad-spectrum abx within 90 days

Add:

  • 1 g · q8h · IV
VRE coverage
  • Prior VRE colonization
  • Liver transplant candidate / recipient
  • Prolonged hospitalization

Add:

  • 6–8 mg/kg · q24h · IV

    Or linezolid 600 mg q12h.

4. Directed Therapy

Once organism identified, narrow:

  • E. coli / Klebsiella, susceptible: ceftriaxone or step-down to oral FQ if susceptible × 5 days total.
  • ESBL E. coli / Klebsiella: meropenem (carbapenem) × 5–7 days.
  • Pneumococcus, susceptible: ceftriaxone × 5 days.
  • Enterococcus faecalis: ampicillin 2 g q4h × 5–7 days (or amp-sulbactam).
  • MRSA: vancomycin AUC-guided × 7 days minimum (and rule out alternative source / secondary).
  • Candida: echinocandin × 14 days from first negative + remove any catheter / drain in ascites. Consider secondary peritonitis or perforated viscus.

Source control: SBP is by definition without an evident source — but if polymicrobial, anaerobes, or clinical picture suggests secondary peritonitis (high ascites protein, low glucose, high LDH, multiple organisms), pursue imaging (CT abdomen/pelvis) and surgical / IR evaluation.

Adjuncts:

  • Albumin 1.5 g/kg day 1 + 1 g/kg day 3 if Cr >1, BUN >30, bili >4 (or NNT~5 to prevent HRS and mortality).
  • Avoid non-selective β-blockers during AKI / septic shock — restart only when stable.
  • Hold diuretics during AKI; restart cautiously.

5. Monitoring

Resolution: repeat paracentesis at 48 hours if not clinically improving — PMN count should drop ≥25%. Persistent ≥250 PMN or rising at 48 h → broaden empirics + image for secondary peritonitis (perforated viscus, abscess).

Outcomes: in-hospital mortality 20–30% historically; recurrent SBP rate ~70% at 1 year without secondary prophylaxis.

Toxicity: ceftriaxone biliary sludge / cholelithiasis with prolonged use; pip-tazo + vanc nephrotoxicity; FQ tendinopathy / QT / CDI.

After discharge: lifelong secondary prophylaxis (FQ daily) for any patient who survives an SBP episode. Refer for liver transplant evaluation if not already.

Pearls

Diagnose with paracentesis on every cirrhotic admission with ascites — fever, abdominal pain, encephalopathy, AKI, or any decompensation. PMN ≥250 = treat (don't wait for cultures). Empirically narrow ceftriaxone works for community-acquired SBP but fails healthcare-associated SBP — distinguish by recent hospitalization, abx within 90 days, prophylaxis on FQ, or nosocomial onset >48 h after admission. Albumin saves lives — Cr >1, BUN >30, bili >4 → 1.5 g/kg day 1 + 1 g/kg day 3, NNT ~5 to prevent HRS/death. Polymicrobial, anaerobes, or low glucose / high protein ascites = secondary peritonitis — image + surgical eval; don't treat as SBP. Lifelong prophylaxis after first SBP with daily FQ — but watch for FQ-resistant pathogens at next admission.

References