Accuracy of Leukocyte Esterase Reagent Strip (LERS) test for rapid bedside screening of spontaneous bacterial peritonitis: An observational study

INTRODUCTION: Spontaneous bacterial peritonitis (SBP) is a frequent and severe complication in cirrhotic patients with ascites. SBP is generally diagnosed based on an increased number of polymorphonuclear neutrophils in the ascitic fluid (>250/mm(3)) and positive culture. Usually fluid analysis and culture take time and precious hours are lost in starting therapy. Leukocyte Esterase Reagent Strips (LERS) have consistently given a high negative predictive value (>95% in the majority of the studies). AIMS AND OBJECTIVES: Aim was to evaluate the diagnostic utility of leukocyte esterase reagent strip for rapid diagnosis of SBP in patients who underwent abdominal paracentesis and to calculate the sensitivity, specificity, positive, and negative predictive values. METHODOLOGY: The study was carried out on 64 patients with ascites. Cell count of AF as determined by colorimetric scale of Multistix 10 SG reagent strip was compared with counting chamber method (PMNL count ≥250 cells/mm(3) was considered positive). RESULTS: Of the 64 patients SBP was diagnosed in 17 patients, 47 patients were negative for SBP by manual cell count. At cut off of 2+; sensitivity to diagnose SBP was 100%; specificity of 94%; PPV being 57% and NPV of 94%. at the cut off level of 3+; sensitivity decreased down to 76%; specificity increased to 100%; PPV of 100% and NPV of 93.75%. Overall accuracy at 2 + and 3 + was respectively 94.5% and 93.75%. CONCLUSION: In this study we have found good sensitivity and specificity for the prompt detection of elevated polymorphonuclear neutrophil count. A negative test result excludes SBP with a high degree of certainty. Thus, it represents a convenient, inexpensive, simple bedside screening tool for SBP diagnosis.