Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology

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pISSN 2288-0585 eISSN 2288-6850

Investigation of Positive Streptococcus pneumoniae Urinary Antigen Test Results in a Korean University Hospital

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2010 March, Volume 13, Issue 1, pages 14-18.

https://doi.org/10.5145/ACM.2010.13.1.14

Investigation of Positive Streptococcus pneumoniae Urinary Antigen Test Results in a Korean University Hospital

In-Suk Kim1, Eun-Ha Koh1, Sunjoo Kim1, Kook Young Maeng1, Hyun Ju Jung2
Department of Laboratory Medicine, Institute of Health Sciences, 1Gyeongsang National University School of Medicine, Jinju, 2Masan Medical Center, Masan, Korea

Abstract

Background: The Streptococcus pneumoniae urinary antigen test (SPUAT) (Binax Now, USA) was developed for detecting polysaccharide C in urine samples for rapid diagnosis of pneumococcal pneumonia, the most common cause of community-acquired pneumonia (CAP). To validate positive results of these tests, we retrospectively investigated all positive results obtained from the emergency room of a Korean university hospital among patients with suspected CAP. 

Methods: One hundred twenty-three positive SPUAT results were abstracted and analyzed from the authors’ laboratory information system among the SPUAT results performed from 1,143 pneumonic patients admitted from the emergency room of a university hospital between 2007 and 2008. Medical records, including conventional microbiologic analysis results, were reviewed in detail for all positive test results. 

Results: Among 123 patients with the positive SPUAT results, 24 patients were excluded due to hospitalization history during the preceding month. Nine of 99 patients (9.1%) with suspected CAP had confirmed pneumococcal pneumonia upon conventional sputum or blood culture. Thirty-five positive results (35.4%) showed other microorganisms upon conventional methods, which might be due to possible cross-reactivity. Among those, 23 positive results were considered bacterial pneumonic agents, and 12 positive results were regarded as urinary tract infection strains or contaminating agents. Fifty-five positive SPUAT results (55.6%) showed negative conventional microbiologic growth, and some positive SPUAT results might be caused by true pneumococcal infection although without cultural evidence. 

Conclusion: Our retrospective study demonstrated that a positive SPUAT result typically does not agree well with conventional culture methods, suggesting that the value of a positive SPUAT result in etiology determination may be limited under practical conditions in a university hospital. (Korean J Clin Microbiol 2010;13:14-18)

Keywords

Streptococcus pneumoniae, Bacterial antigens, Urinary antigen test, Cross-reactivity