Colorimetric test for early diagnosis of spontaneous bacterial peritonitis.

Introduction and Objectives

The diagnosis of spontaneous bacterial peritonitis (SBP) requires biochemical analysis that can sometimes take time, so having an effective and rapid method could shorten the time to start the antimicrobial and reduce the risk of complications. Objective: To validate the colorimetric test (reagent strips) in the diagnosis of SBP.

Materials and Patients

Observational, prolective, and analytical study of the colorimetric test for the diagnosis of PBE. Diagnostic paracentesis was performed in patients with suspected PBE, for the analysis of the fluid by means of the colorimetric scale of the Mission test strip and compared with the cytochemical analysis in the laboratory (polymorphonuclear ≥ 250 cells/mm³). To assess the test strip as a diagnostic test, a cut-off point of strip reading ≥15 leukocytes is used. A 2 × 2 table is used to compare the positives and negatives of PBE by both cytochemical and dipstick methods. S, E, PPV and NPV were calculated.

Results

42 patients with ascites and suspected SBP were included. Of these, 24 patients (57.14%) were in Child-Pugh stage C, 17 patients (40.27%) were in Child-Pugh stage B and only 1 patient (2.38%) was in Child-Pugh stage A. The causes of chronic liver disease were alcohol consumption in 17 patients (40.27%), MASLD in 15 patients (35.71%), autoimmune liver disease in 4 patients (9.52%), unaffiliated etiology in 4 patients (9.52%), infection secondary to hepatitis C virus in 2 patients (4.76%). Of the total, 23 patients (54.7%) were female with a mean age of 54 years (SD ± 12.06). Thirteen patients were diagnosed with PBE, 81% of them with grade II ascites. The sensitivity of the dipstick compared to the cytochemical method was 92.3%, its specificity 86.2%, its positive predictive value (PPV) 99.4%, and its negative predictive value (NPV) 98.6%.

Conclusions

Colorimetry (test strips) show adequate sensitivity and specificity, making them a low-cost, easy-to-use, but above all quick to interpret tool for early initiation of antimicrobial therapy in patients with ascites and spontaneous bacterial peritonitis. Although the sample is small, it shows an interesting trend that should be confirmed.

Ethical statement: The research was carried out in accordance with the Helsinki Declaration of the World Assembly 2013.

Declaration of interests: None.

Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.