Spontaneous Bacterial Peritonitis
GENERAL PRINCIPLES
• Spontaneous bacterial peritonitis (SBP) is an infectious complication of portal hypertension-related ascites defined as gt;250 neutrophils#8725;#956;L in the ascites fluid.
• Bacterascites is defined as culture-positive ascites in the presence of normal neutrophil counts (lt;250 neutrophils#8725;#956;L) in the ascites fluid. This condition may be spontaneously reversible or the first step in the development of SBP. In the presence of signs or symptoms of infection, bacterascites should be treated like SBP.
• Risk factors for SBP include ascites fluid protein concentration lt;1 mg#8725;dL, acute GI bleeding, and a prior episode of SBP.
DIAGNOSIS
Clinical Presentation
SBP may be asymptomatic. Clinical manifestations include abdominal pain and distention, fever, decreased bowel sounds, and worsening hepatic encephalopathy. Cirrhotic patients with ascites and evidence of any clinical deterioration should undergo diagnostic paracentesis to exclude SBP.
Diagnostic Testing
The diagnosis is confirmed when gt;250 neutrophils#8725;#956;L are found in the ascites fluid. Gram stain reveals the organism in only 10%-20% of samples.
• Ascites cultures are more likely to be positive when 10 mL of the fluid is inoculated into two blood culture bottles at the bedside.
• The most common organisms are Escherichia coli, Klebsiella, and Streptococcus pneumoniae. Polymicrobial infection is uncommon and should lead to the suspicion of secondary bacterial peritonitis. Checking total protein, LDH, and glucose on ascites fluid is helpful in distinguishing secondary bacterial peritonitis from SBP.
TREATMENT
Medications
• Patients with SBP should receive empiric antibiotic therapy with IV third-generation cephalosporins (ceftriaxone, 2 g IV daily, or cefotaxime, 2 g IV q6-8h, depending on renal function).
Therapy should be tailored based on culture results and antibiotic susceptibility. Paracentesis should be repeated if no clinical improvement occurs in 48-72 hours, especially if the initial fluid culture was negative.32• Oral quinolones can be considered a substitute for IV third-generation cephalosporins in the absence of vomiting, shock, grade II (or higher) hepatic encephalopathy, or serum creatinine gt;3 mg#8725;dL.
• Patients with lt;250 neutrophils#8725;#956;L in the ascites fluid and signs or symptoms of infection (fever or abdominal pain or tenderness) should also receive empiric antibiotic therapy.
• Concomitant use of albumin 1.5 g/kg body weight at the time of diagnosis and 1.0 g/kg body weight on day 3 improves survival and prevents renal failure in SBP.32
PRIMARY PROPHYLAXIS (NO PRIOR HISTORY OF SBP)
Patients with severe liver disease with ascitic fluid protein lt;1.5 mg/dL along with impaired renal function (creatinine #8805;1.2, blood urea nitrogen #8805;25, or serum Na #8804;130) or liver failure (Child score #8805;9 and bilirubin #8805;3) should be treated with long-term norfloxacin 400 mg PO daily.
SECONDARY PROPHYLAXIS (AFTER THE FIRST EPISODE OF SBP)
Ciprofloxacin 500 mg PO daily or trimethoprim-sulfamethoxazole single strength one tab PO daily is the treatment of choice for prevention of recurrent SBP.33