SEROLOGICAL AND FECAL ELISA-BASED DETECTION OF HELICOBACTER PYLORI: INSIGHTS INTO ACTIVE VERSUS PAST INFECTIONS

Abstract

Background: Helicobacter pylori (H. pylori) is a prevalent gastrointestinal pathogen associated with chronic gastritis, peptic ulcer disease, and gastric cancer. Differentiating between active and past infections is critical for effective clinical management. Serological enzyme-linked immunosorbent assay (ELISA) detects H. pylori-specific antibodies but cannot distinguish between current and previous exposure. In contrast, fecal antigen ELISA directly identifies bacterial antigens, making it a more reliable tool for diagnosing active infections. Comparing the diagnostic performance of these methods is essential to refine non-invasive diagnostic strategies.

Objective: This study aimed to evaluate the accuracy of serological and fecal ELISA-based methods in detecting H. pylori infection by assessing their sensitivity, specificity, and correlation with clinical symptoms.

Methods: Following ethical approval (ERC #139/04/2022), this cross-sectional study was conducted in the Department of Pathology, Shaikh Zayed Hospital, Lahore. A total of 100 participants were enrolled, comprising 50 symptomatic patients diagnosed with gastritis or peptic ulcer via endoscopy and 50 asymptomatic individuals. Patients with prior H. pylori eradication therapy or recent use of antibiotics, proton pump inhibitors, or bismuth compounds were excluded. Blood and stool samples were collected for serological and fecal ELISA testing. Sensitivity, specificity, and predictive values were calculated, and statistical analyses were performed to compare both diagnostic methods.

Results: The study population included 56% males and 44% females, with an age range of 40–60 years. Serological ELISA demonstrated a sensitivity of 60% and specificity of 90%, detecting past or current exposure. Fecal antigen ELISA showed a higher diagnostic accuracy, with 68% of symptomatic patients and 12% of asymptomatic individuals testing positive, confirming its superiority in detecting active infections. The positive predictive value (PPV) of serological ELISA was 85.7%, while its negative predictive value (NPV) was 69.2%. In contrast, fecal antigen ELISA had a PPV of 85.0% and an NPV of 73.3%.

Conclusion: Although serological ELISA is a widely available screening tool, its clinical utility is limited due to its inability to distinguish active from past infections. Fecal antigen ELISA demonstrated greater specificity and diagnostic accuracy, making it the preferred method for detecting active H. pylori infections. Integrating molecular diagnostics with ELISA-based testing could further enhance diagnostic precision and guide treatment decisions.