Spontaneous bacterial peritonitis (SBP) is defined as infection of ascitic fluid without evidence of an intra-abdominal surgically treatable source; depending on the clinical context, imaging by CT may be needed to exclude such a source.
SBP is a common complication of ascites due to cirrhosis; the lower the ascitic fluid albumin concentration (prior to infection), the higher the risk. Aerobic Gram-negative bacteria, especially Escherichia coli, are the commonest causative organisms. Features of SBP include fever (70%), abdominal pain (60%), abdominal tenderness (50%) and change in mental state (50%). It may be complicated by the hepatorenal syndrome (in up to 30%).
The diagnosis of SBP is based on the finding of >250 neutrophils/mm3 in ascitic fluid. If the neutrophil count is less than this, but there are features of sepsis, treatment should be given for SBP, pending the result of culture; if the patient is well, hold off antibiotic therapy and remeasure the cell count in 48 hours.
- Treat with third-generation cephalosporin, for example cefotaxime 2g 8-hourly IV for 5 days, followed by a quinolone PO for 5 days.
- If serum creatinine is >88micromol/L, urea is >10.7 mmol/L, or bilirubin is >68micromol/L, give human albumin solution 1.5g/kg IV at diagnosis and 1g/kg 48h later to reduce the incidence of hepatorenal syndrome.
- Repeat diagnostic paracentesis at 48hours: if the neutrophil count has not reduced by 25% or the patient has ongoing signs of sepsis, discuss changing the antibiotic regimen with your microbiologist.
This is indicated for:
- Patients with cirrhosis who present with gastrointestinal bleeding (Chapters 73 and 74).
- Patients with cirrhosis and ascites, with ascitic fluid protein <10g/L, who require hospital admission for another reason.
- Patients with cirrhosis and ascites, with ascitic fluid protein <15g/L and:
- Impaired renal function (serum creatinine >106micromol/L or urea >8.9 mmol/L)
- Low plasma sodium ≤130 mmol/L or
- Liver failure (Child-Pugh score ≥9 and serum bilirubin ≥51micromol/L
- Patients who have had one or more episodes of SBP, in whom the recurrence rate is up to 70% at one year.
Discuss the choice of prophylaxis with a hepatologist or microbiologist.