[Usefulness of reagent strips for the diagnosis of spontaneous bacterial peritonitis]

Spontaneous bacterial peritonitis (SBP) is one of the potentially life-threatening complications for patients with liver cirrhosis, and it has a mortality rate of over 20%. Early diagnosis of SBP and immediate use of an adequate antibiotic therapy are very important for achieving a better prognosis. The aim of our study was to assess the usefulness of reagent strips for making the rapid diagnosis of SBP.

A diagnostic paracentesis procedure was performed upon hospital admission in 257 cirrhotic patients (187 males, 70 females; mean age: 54 years) with ascites. Each fresh sample of ascitic fluid was tested using a reagent strip, and the result was scored as 0, 1+, 2+ or 3+. The leukocyte count, polymorphonuclear cell count, blood bottle culture, and chemistry of ascites were also done.

We diagnosed 79 cases of SBP and 2 cases of secondary bacterial peritonitis by means of the polymorphonuclear cell count and the classical criteria. When a reagent strip result of 3+ was considered positive, the test's sensitivity was 86% (70 of 81), the specificity was 100% (176 of 176), and the positive predictive value was 94%. Furthermore, when a reagent strip result of 2+ or more was considered positive, the test sensitivity was 100% (81 of 81), the specificity was 99% (174 of 176), and negative predictive value was 99%.

The use of reagent strips is a very sensitive and specific tool for the rapid diagnosis of SBP in cirrhotic patients. A positive result should be an indication for empirical antibiotic therapy, and a negative result may be useful as a screening test to exclude SBP.