Value of reagent strips in the rapid diagnosis of spontaneous bacterial peritonitis.

Background/aims: Spontaneous bacterial peritonitis is a severe complication in cirrhotic patients with ascites. Early antibiotics are essential to improve the prognosis. An ascites neutrophil count >250/mm3 is an indication for antibiotic therapy. However this procedure requires intensive labor and is not available in all hospitals on emergency setting. The aim of this study was to assess the utility of Human-Test Combina strips for the rapid diagnosis of spontaneous bacterial peritonitis. The interobserver variability in the result reading was also evaluated.

Methodology: A prospective study of 109 consecutive ascitic fluid samples colected from 55 patients was carried out. The results of the reagent strips were compared with the neutrophil count by conventional optical microscopy. Interobserver agreement was tested in 37 cases.

Results: The prevalence of infection was 8.3%. Reagent strips had sensitivity, specificity, positive and negative predictive values of 78%, 88%, 37% and 98% for a cut-off level > or =2 and 67%, 98%, 75% and 97% for > or =3, respectively. Concordance between investigators was 100%.

Conclusions: Reagent strips are a rapid, simple and easily available method for the diagnosis of spontaneous bacterial peritonitis. A positive result should be an indication to start antibiotics and a negative result can be useful to exclude the possibility of infection.