Diagnostic value of two reagent strips (Multistix 8 SG and Combur 2 LN) in cirrhotic patients with spontaneous bacterial peritonitis and symptomatic bacterascites

Abstract

Objective: Spontaneous bacterial peritonitis is a life-threatening complication in patients with liver cirrhosis requiring a rapid diagnosis. We have tested two reagent strips, Multistix 8 SG and Combur 2 LN for bedside diagnosis of spontaneous bacterial peritonitis and symptomatic bacterascites, a variant of spontaneous bacterial peritonitis.

Methods: Responses of the two strips in colorimetric scale were compared with results given by cyto-bacteriological analysis of ascitic fluid. Results with positivity in grades 1 and 2 of colorimetric scale were analyzed.

Results: Four hundred and forty three paracentesis were performed in 116 patients including 46 samples of ascitic fluid with spontaneous bacterial peritonitis occurring in 25 patients and 20 samples of ascitic fluid with symptomatic bacterascites occurring in 17 patients. Forty two percent of spontaneous bacterial peritonitis were culture-negative neutrocytic ascites, gram-positive pathogens and enterobacteriaceae were responsible for 36% and 21% episodes of spontaneous bacterial peritonitis and 71% and 29% episodes of symptomatic bacterascites respectively. Fifty seven percent of spontaneous bacterial peritonitis had polymorphonuclear cell count<1000/mm3. For spontaneous bacterial peritonitis diagnosis, grade 1 positive Multistix and Combur tests had a sensitivity of 69.6% and 80.4% respectively, and a negative predictive value of 96% and 97.3%. Grade 2 positivity increased specificity to 98% and 99.2% and positive predictive value to 75% and 91% for the two strips respectively. Grade 1 positive tests had a sensitivity of 100% and 90% and a negative predictive value of 100% and 99.4% respectively for diagnosis of spontaneous bacterial peritonitis with polymorphonuclear count > 1000/mm3. For symptomatic bacterascites diagnosis, grade 1 positive tests had a sensitivity of 22.4% and 44.4% respectively and a negative predictive value of 96% and 97%.

Conclusion: Although Combur had a higher sensitivity than Multistix for the diagnosis of spontaneous bacterial peritonitis, sensitivity of the two strips remains low with polymorphonuclear cell count<1000/mm3. Grade 2 positive Combur test had an acceptable positive predictive value. Sensitivity of both strips is insufficient for diagnosis of symptomatic bacterascites. Rapid cyto-bacteriological analysis of ascitic fluid remains necessary for diagnosis of these complications.