Spontaneous bacterial peritonitis (SBP) is defined as a bacterial infection of the ascitic fluid without a surgically treatable intra-abdominal infection source. SBP is a common, severe complication in cirrhosis patients with ascites, and if left untreated, in-hospital mortality may exceed 90%. However, the incidence of SBP has been lowered to approx. 20% through early diagnosis and antibiotic therapy. There are three types of SBP. Bacterial translocation from the gastrointestinal tract is the most common source of SBP. Distinguishing SBP from secondary bacterial peritonitis is essential because the conditions require different therapeutic strategies. The standard treatment for SBP is prompt broad-spectrum antibiotic administration and should be tailored according to community-acquired SBP, healthcare-associated or nosocomial SBP infections, and local resistance profile. Albumin supplementation, especially in patients with renal impairment, is also beneficial. Selective intestinal decontamination is associated with a reduced risk of bacterial infection and mortality in the high-risk group.
|Ascites Fluid||Classic SBP||CNNA 1||MNB 2|
|PMN count (cells/mm3)||≥250||≥250||<250|
Spontaneous bacterial peritonitis (SBP) should be suspected in patients with cirrhosis who develop signs or symptoms, such as fever (69%), abdominal pain (59%), altered mental status (54%), abdominal tenderness (49%), diarrhea (32%), ileus (30%), hypotension/shock (21%), or hypothermia (17%) . However, 10% of cases show no signs or symptoms, partly because a large volume of ascites prevents contact of the visceral and parietal peritoneal surfaces to elicit the spinal reflux that cause abdominal rigidity .
A diagnostic paracentesis should be performed in all patients with cirrhosis and ascites who require emergency room care or hospitalization, who demonstrate or report signs/symptoms mentioned above in the clinical presentations, or who present gastrointestinal bleeding, in order to confirm evidence of SBP . However, low clinical suspicion for SBP does not preclude the necessity for paracentesis, since 10% of cases have no signs or symptoms .
Ascitic fluid tests should include cell count with a differential, Gram stain, culture, total protein, and albumin to calculate the serum-ascites albumin gradient (SAAG), if not already known . When the diagnosis of cirrhosis is not definite, an ascites SAAG greater than or equal to (≧) 1.1 g/dl is ascribed to portal hypertension with approximately 97% accuracy . Total ascitic fluid protein concentration should be measured to assess the risk of SBP since patients suffering from ascites with a total protein concentration lower than (<) 1.5 g/dL are at increased risk of SBP .
A diagnosis of (1) classic SBP is made if PMN count in the ascitic fluid is ≥250 cells/mm3, culture results are positive, and secondary causes of peritonitis are excluded . A potential source of error in PMN count is hemorrhage into the ascitic fluid, such as with traumatic paracentesis, which can cause both red and white blood cells to enter the ascites. A corrected PMN count should be calculated if there are bloody ascites by subtracting one PMN from the absolute PMN count for every 250 red cells/mm3 . Distinguishing SBP from secondary bacterial peritonitis is essential because the conditions require different therapeutic strategies. Mortality from SBP can be as high as 85% if a patient undergoes an unnecessary exploratory laparotomy , while mortality of secondary bacterial peritonitis can exceed 80% if treatment consists of antibiotics without surgical intervention .