Rapid diagnosis of spontaneous bacterial peritonitis by use of reagent strips

Abstract

We studied the use of reagent strips for diagnosis of spontaneous bacterial peritonitis (SBP) in cirrhotic patients with ascites. A reagent strip for leukocyte esterase designed for the testing of urine with a colorimetric 5-grade scale (0 to 4) was used to evaluate ascitic fluid in 228 nonselected paracentesis performed in 128 cirrhotic patients. We diagnosed 52 SBP and 5 secondary bacterial peritonitis by means of polymorphonuclear cell count and classical criteria. When we considered positive a reagent strip result of 3 or 4, sensitivity was 89% (51 of 57), specificity was 99% (170 of 171), and positive predictive value was 98%. When we considered positive a reagent strip result of 2 or more, sensitivity was 96% (55 of 57), specificity was 89% (152 of 171), and negative predictive value was 99%. In conclusion, the use of reagent strips is a rapid, easy to use, and inexpensive tool for diagnosis of ascitic fluid infection. 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.