Diagnostic Performance of Streptococcus pneumoniae Urinary Antigen Assay: A Cross-sectional Study on Comparative Analysis of Bacterial Culture and Molecular Detection in Pneumococcal Infections

Abstract

Introduction: Pneumonia is the most prevalent infection worldwide, leading to hospitalisation and contributing to mortality rates. Among the bacterial agents associated with CommunityAcquired Pneumonia (CAP), Streptococcus pneumoniae remains the most common. Conventional microbiological diagnostic tests have various limitations, including issues with sample collection, prior antibiotic administration, and delayed specimen transport. Urinary Antigen Testing (UAT) shows promise in rapidly identifying the causative agent of CAP, allowing for targeted therapy. Aim: To evaluate the diagnostic accuracy of the pneumococcal UAT in identifying CAP. Materials and Methods: A cross-sectional analytical study was conducted over a period of one year from June 2022 to May 2023 at SRM Medical College Hospital and Research Centre, Kattankulathur, Chengalpattu, Tamil Nadu, India. A total of 38 patients (>18 years of age) with clinically suspected CAP and who satisfied the clinical criteria for CAP were recruited for the study. Respiratory specimens were subjected to bacterial culture, real-time Polymerase Chain Reaction (PCR), and UAT using the Fluorescent Immunoassay (FIA) to detect Streptococcus pneumoniae. The sensitivity, specificity, positive and negative predictive values, and accuracy of the pneumococcal UAT for detecting CAP were assessed. Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) software, version 21.0. Results: The study revealed a female predominance 22 (57.89%). Bacterial culture and real-time PCR identified 7 (18.42%) of patients with S. pneumoniae, while the UAT only detected 1 (2.63%). The pneumococcal UAT showed low sensitivity (14.29%), high specificity (100%), and satisfactory accuracy (84.21%). Conclusion: The pneumococcal UAT, with its straightforward technology, ease of use, rapid results, non invasive approach, cost-effectiveness, and high specificity and accuracy, could be favoured over bacterial culture and molecular techniques for ruling out CAP.