The value of ascitic fluid calprotectin and calprotectin-to-albumin ratio in the diagnosis and prognosis of spontaneous bacterial peritonitis

Introduction
Spontaneous bacterial peritonitis (SBP) is a potentially fatal condition, characterized by infection of ascitic fluid (AF) in the absence of any intra-abdominal surgically treatable source of infection. It is the most frequent and severe complication of cirrhotic ascites. SBP is a condition that requires a high index of suspicion, rapid and accurate diagnosis, in addition to prompt and effective therapy.
Aim
The aim of this study was to evaluate AF calprotectin as a diagnostic marker in detecting SBP. In addition, we have evaluated AF calprotectin-to-albumin ratio in the diagnosis and prognosis of SBP.
Patients and methods
A total of 72 patients with cirrhotic ascites were included in this study. They were divided into two groups: SBP group included 50 patients with cirrhotic ascites and SBP diagnosed by presence of polymorphonuclear leukocyte count at least 250 cells/mm in AF with or without positive AF culture, and non-SBP group included 22 patients with cirrhotic ascites without evidence of SBP. All patients were subjected to complete clinical evaluation, laboratory investigations, diagnostic abdominal paracentesis, serum and AF C-reactive protein levels, which were assessed quantitatively, and AF calprotectin levels, which were measured by quantitative sandwich enzyme-linked immunosorbent assay.
Results
AF calprotectin was significantly elevated in patients with SBP in comparison with non-SBP patients (<0.001), with the best cutoff value for the detection of SBP (372 ng/ml) with a sensitivity, specificity, positive predictive value, negative predictive value, and an accuracy of 100% for each. Moreover, there was a positive correlation with total leukocytic count, polymorphonuclear leukocyte, and C-reactive protein in serum and AF. Moreover, calprotectin-to-albumin ratio was increased in SBP group versus non-SBP group (<0.001).
Conclusion
AF calprotectin can be used as a valuable marker in rapid diagnosis of SBP. Moreover, calprotectin-to-albumin ratio in ascites is useful in the diagnosis of SBP, as well as it provides prognostic information on short-term survival of patients with SBP with follow-up treatment.