Spontaneous bacterial peritonitis

Clinical Manifestations

1. Develops in large, clinically obvious ascites 2/2 cirrhosis
2. Fever - 70%
3. Abdominal pain (diffuse) - 60%
4. Altered mental status - 55%
5. ~15% of patients have no signs/symptoms!

Diagnosis

1. Paracentesis results supporting a diagnosis of SBP:
   1. Absolute neutrophil count > 250PMNs/microL
   2. SAAG > 1.1
   3. Total protein < 1 and Glucose > 50 (otherwise concern for 2^o bacterial peritonitis)
2. There is no platelet count or INR that is a contraindication to paracentesis

Distinction of spontaneous from secondary bacterial peritonitis

1. Importance
   1. Mortality of 2^o bacterial peritonitis approaches 100 percent if tx is only antibiotics without sx
   2. Mortality of unncessary ex lap in patient w/ SBP and wrongly suspected 2^o bacterial peritonitis ~80%
2. Laboratory findings
   1. Neutrocytic fluid (PMN ≥250) with two or more of following = strong evidence of 2^o bacterial peritonitis:
      1. 1. Total protein concentration >1 g/dL (10 g/L)
      2. 2. Glucose concentration <50 mg/dL (2.8 mmol/L)
      3. 3. LDH greater than upper limit of normal for serum
   2. Should strongly suspect if ascitic alk phos >240
   3. Gram Stain
      1. Large numbers of different bacterial forms
3. Imaging
   1. If evidence of 2^o bacterial peritonitis obtain abdominal imaging
      1. If no evidence of free air or contrast extravasation then surgery is not indicated

Treatment

1. Antibiotics
   1. SBP
      1. Broad-spectrum covering gram + and gram -
         1. 3rd-generation cephalosporin is agent of choice:
            1. Cefotaxime 2g IV q8hr or Ceftriaxone 1-2g IV q12-24hr
         2. If beta-lactam allergy consider ciprofloxacin 400mg IV q12hr>
   2. 2ndary bacterial peritonitis
      1. 3rd-generation cephalosporin + metronidazole
2. Albumin
   1. Decreases incidence of renal failure
   2. 1.5g/kg at time of diagnosis and 1g/kg on day 3

Source

Rosen's, UpToDate, Thomsen TW. Paracentesis. N Engl J Med 2006; 355