Ascitic Fluid Calprotectin as an Accurate Diagnostic Marker for Spontaneous Bacterial Peritonitis

Spontaneous bacterial peritonitis (SBP) is an infection of the ascitic fluid in patients with liver cirrhosis and portal hypertension. There is no obvious surgical cause as perforation or intraabdominal inflammatory focus as abscess. Up to 30% of the ascitic patients will develop SBP.

SBP is attributed to immune dysfunction, bacterial translocation, circulatory dysfunction and inflammatory status. SBP is diagnosed by ascitic fluid analysis . SBP was defined as polymorphonuclear leucocyte count (PMN) >250/mm3 in ascitic fluid, . Not all cases are associated with positive ascitic fluid cultures.

There are variants of ascitic fluid infections as culture-negative neutrocytic ascites, monomicrobial non-neutrocytic bacterascites, polymicrobial bacterascites and secondary bacterial peritonitis.

The advent of the SBP carries a poor prognosis where the hospital mortality ranged from 10 to 50%. As a consequence, any patient with SBP should be assessed for liver transplantation. Immediate treatment with antibiotics and IV albumin should be initiated.

Studies were conducted on alternatives of the ascitic PMN count as high sensitivity C-reactive protein (hsCRP), serum procalcitonin, urinary lipocalin, ascitic lactoferrin, homocysteine and fecal or ascitic calprotectin.

The gold standard test for SBP is ascitic fluid analysis with measurement of the PMN. It is useful for the diagnosis and monitoring of treatment. The culture of the ascitic fluid may be positive if was done correctly .

There is a variant of SBP that is called culture-negative neutrocytic ascites. It is characterized by elevated ascitic fluid PMN but the culture is negative. It is managed exactly as classic SBP. Such cases would be missed if cultures were not done The manual PMN counting is time consuming, laborious and required some experience to avoid intra- and inter-observer variability. So, a simple rapid bedside test would be useful clinically.

Calprotectin is acute-phase inflammatory protein that is released from the PMN. Calprotectin has anti-proliferative and antimicrobial properties. Calprotectin is used clinically widespread in the diagnosis and monitoring treatment of inflammatory bowel disease .