Spontaneous Bacterial Peritonitis (SBP)
Bailey DeCoursey
Background
- Infection of ascitic fluid without evidence of a surgical intra-abdominal source
- Present in approximately 1/3 of patients with cirrhosis who are hospitalized
- Presentation: fever, abdominal pain, encephalopathy, renal failure, acidosis, and/or leukocytosis. However, up to one‐third of the patients with spontaneous infections may be entirely asymptomatic or present with only encephalopathy and/or AKI
- Pathophysiology: Combination of GI bacterial flora overgrowth, reduced liver protein production (low complement levels), impaired phagocytic cell function leading to inability to clear pathogens
Evaluation
- Any pt with cirrhosis and ascites who is admitted should have diagnostic para to r/o 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.
- PMN > 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 with bacterascites should NOT receive antibiotics as it is likely a contaminant (however, repeat paracentesis should be performed to exclude progression to SBP). You will also frequently see culture-negative SBP (neutrocytic ascites) which SHOULD be treated (see below).
Management
- 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, should give zosyn +/- vanc if prior infection or positive swab for MRSA. Daptomycin should be added with hx of VRE infection instead of vanc.
- Finally, in patients with current or recent exposure to zosyn consider meropenem for MDR coverage.
- IV albumin 1.5 g/kg on day 1 and 1g/kg on day 3
- NSBB do not need to be discontinued in patients with SBP unless hypotensive (mean arterial pressure <65mmHg). If stopped, the timing of re-initiation is based on recovery of blood pressure
- 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. Consider secondary bacterial peritonitis.
- Prophylaxis:
- Ciprofloxacin 500mg BID (preferred) or Bactrim one DS tablet BID x 5-7 days
- IV ceftriaxone 1g daily is currently the recommended antibiotic in patients with hemorrhage
- Outpatient 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 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 2/3 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 |
