Original article Address for correspondence: Behrooz Ataei, Associate Professor, Infectious Diseases and Tropical Medicine Research Center, Isfahan Uni- versity of Medical Sciences, Isfahan, Iran. Email: ataei@med.mui.ac.ir Received: 17.11.2011; Revised: 14.12.2011; Accepted: 24.01.2012 | March 2012 Special Issue (2) | Journal of Research in Medical Sciences S183 Assessment of a urinary antigen test in inpatients with pneumococcal pneumonia Alireza Emami Naeini 1 , Behrooz Ataei 1 , Kiana Shirani 2 , Mojtaba Akbari 3 1 Associate Professor, Infectious Diseases and Tropical Medicine Research Center, Isfahan University of Medical Sciences, Is- fahan, Iran. 2 Resident, Department of Infectious and Tropical Medicine, School of Medicine And Student Research Committee, Isfahan University of Medical Sciences, Isfahan, Iran. 3 Epidemiologist, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. Background: Streptococcus pneumonia is one of the most important pathogens in community- acquired pneumonia. Diagnosis of this disease by conventional methods is often problematic. Therefore, a sensitive and specific diagnostic method can be helpful. The aim of this study was to evaluate the sensitivity and specificity of a rapid urinary antigen detection test in patients with pneumonia. Materials and Methods: In a cross-sectional study, a total number of 66 patients including 47 (71.2%) males and 19 (28.8%) fe- males over 18 years old were divided into two group. The case group included 33 patients with pneumococcal pneumonia while the control group consisted of 33 patients with non-pneumococcal pneumonia. We compared the sensitivity and specificity of an in-vitro rapid immunochromatography (IC) pneumococcal urinary antigen test between the two groups. Results: While 23 patients (69.7%) in the case group had positive urine antigen test results, no control patient with positive urine antigen test result was detected. The sensitivity of urinary antigen test in the case group was 69.70% (95% CI: 51.29-84.38). The specificity of the test was determined as 100% (95% CI: 89.32-100). Positive and negative predictive values of the test were 100% (85.05-100) and 76.74% (61.36-88.23), respectively. Conclusion: Pneumococcal urinary antigen IC test is a sensitive and highly specific method for diagnosis of pneumo- coccal pneumonia. Key words: Urine Antigen, Community-Acquired Pneumonia, Pneumococcal Pneumonia, Pneumococci. INTRODUCTION Streptococcus pneumonia (SP) still remains one of the major pathogens in adults and children world‐ wide. It is responsible for more than 5,000,000 pneumonia cases every year. [1] With a significant mortality rate, it is still considered as a killer dis‐ ease. [1] SP finds its ecological niche in colonizing the nasopharynx. An appropriate culturing would yield pneumococci in up to 40‐60% or greater. [2] When po‐ tentially different protective defenses are sup‐ pressed due to various diseases and environmental factors, pneumococci access to alveoli by micro‐ aspiration. The organism produces several viru‐ lence factors that are involved in the diseases. [3] SP is the leading cause of community‐acquired pneu‐ monia (CAP) and a significant cause of morbidity and mortality in all age groups. [4] The causative role of SP is strongly suggested by microscopic exami‐ nation of Gram‐stained sputum culture 5 and ap‐ proved by blood culture. [2] Microscopic examination and culture of expectorated sputum remain the mainstay of the laboratory evaluation of pneumo‐ nia. [1,5] Failure to determine CAP etiology results from limitations in these routine diagnostic me‐ thods. The diagnosis of pneumococcal pneumonia is frequently problematic. In pre‐antibiotic era, only about 25% of patients had positive blood culture. [6] However, the rates further decrease when antibio‐ tics had been previously administered. [7] Difficulties in obtaining good‐quality sputum and lag time in receiving conventional culture and unavailability of new culture methods in every hospital are the rea‐ sons to seek for new rapid and accurate diagnostic methods. Conventional multiplex polymerase chain reaction (PCR) and novel real time PCR are insuffi‐ ciently sensitive when applied to blood or urine and are not infection specific when applied to respirato‐ ry samples. [8] Urinary pneumococcal antigen detec‐ tion is considered as a possible diagnostic utility. [9] BinaxNOW® (Inverness Medical, Cologne, Germa‐ ny) is an in‐vitro rapid immunochromatographic test (ICT) for the qualitative detection of C polysac‐ charide SP antigen in urine of patients with pneu‐ mococcal pneumonia. [10,11] The aim of this study was to evaluate the sensitivity and specificity of this urinary antigen detection test in inpatients with diagnosis of pneumococcal pneumonia. MATERIALS AND METHODS In a cross‐sectional study, 66 adults with CAP hos‐ pitalized in Alzahra Hospital (Isfahan, Iran) during 2011 were evaluated. CAP was defined as an acute illness occurring in a patient with clinical findings including fever, chills, cough, sputum production, www.mui.ac.ir