The BinaxNOW pneumococcal antigen test: An adjunct for diagnosis of pneumococcal bacteraemia
Background: Culture remains the diagnostic standard for Streptococcus pneumoniae bacteraemia but is limited by time to identification, prior antibiotics and bacterial autolysis. Culture-independent methods for detecting S. pneumoniae include PCR and antigen tests. We evaluated an antigen test on blo...
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| Format: | Article |
| Language: | English |
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AOSIS
2021-04-01
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| Series: | Southern African Journal of Infectious Diseases |
| Subjects: | |
| Online Access: | https://sajid.co.za/index.php/sajid/article/view/244 |
| _version_ | 1823970474666754048 |
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| author | Hafsah D. Tootla Colleen Bamford Chad M. Centner Clinton Moodley |
| author_facet | Hafsah D. Tootla Colleen Bamford Chad M. Centner Clinton Moodley |
| author_sort | Hafsah D. Tootla |
| collection | DOAJ |
| description | Background: Culture remains the diagnostic standard for Streptococcus pneumoniae bacteraemia but is limited by time to identification, prior antibiotics and bacterial autolysis. Culture-independent methods for detecting S. pneumoniae include PCR and antigen tests. We evaluated an antigen test on blood culture broth for the rapid detection of S. pneumoniae bacteraemia.
Method: We collected 212 signal-positive blood cultures, with gram-positive cocci in pairs, chains or with uncertain morphology. The BinaxNOW S. pneumoniae urinary antigen test, Gram stain, culture and lytA PCR were performed on all samples. Diagnostic accuracy of the antigen test and Gram stain with gram-positive cocci in pairs were compared with culture, polymerase chain reaction (PCR) and the composite of culture and PCR.
Results: Streptococcus pneumoniae was isolated in 26% of samples, 66% cultured other gram-positive organisms and 8% of samples had no growth. Sensitivity and negative predictive values of the antigen test were 100%, specificity and positive predictive values were 87% – 88% and 76% – 81%, but increased to 93% – 96% and 96% – 98% when applied to subsets with gram-positive cocci in pairs, or history compatible with respiratory illness or meningitis. Sensitivity (69% – 75%) and specificity (81%) of Gram stain (gram-positive cocci in pairs) were lower than the antigen test even when applied to the same subsets.
Conclusion: Accurate and rapid diagnosis of S. pneumoniae bacteraemia is challenging. Specificity of this antigen test is limited by cross-reactivity with other gram-positive organisms, but could be improved if Gram stain morphology and clinical history are available. The antigen test is a useful adjunct for rapid diagnosis of S. pneumoniae bacteraemia. |
| first_indexed | 2024-12-18T03:13:29Z |
| format | Article |
| id | doaj.art-94789ab4c7ea4bbb9d0fe79603a8f147 |
| institution | Directory Open Access Journal |
| issn | 2312-0053 2313-1810 |
| language | English |
| last_indexed | 2024-12-18T03:13:29Z |
| publishDate | 2021-04-01 |
| publisher | AOSIS |
| record_format | Article |
| series | Southern African Journal of Infectious Diseases |
| spelling | doaj.art-94789ab4c7ea4bbb9d0fe79603a8f1472022-12-21T21:22:58ZengAOSISSouthern African Journal of Infectious Diseases2312-00532313-18102021-04-01361e1e910.4102/sajid.v36i1.244180The BinaxNOW pneumococcal antigen test: An adjunct for diagnosis of pneumococcal bacteraemiaHafsah D. Tootla0Colleen Bamford1Chad M. Centner2Clinton Moodley3Division of Medical Microbiology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa; and, National Health Laboratory Service, Microbiology, Groote Schuur Hospital, Cape TownDivision of Medical Microbiology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa; and, National Health Laboratory Service, Microbiology, Groote Schuur Hospital, Cape TownDivision of Medical Microbiology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa; and, National Health Laboratory Service, Microbiology, Groote Schuur Hospital, Cape TownDivision of Medical Microbiology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa; and, National Health Laboratory Service, Microbiology, Groote Schuur Hospital, Cape TownBackground: Culture remains the diagnostic standard for Streptococcus pneumoniae bacteraemia but is limited by time to identification, prior antibiotics and bacterial autolysis. Culture-independent methods for detecting S. pneumoniae include PCR and antigen tests. We evaluated an antigen test on blood culture broth for the rapid detection of S. pneumoniae bacteraemia. Method: We collected 212 signal-positive blood cultures, with gram-positive cocci in pairs, chains or with uncertain morphology. The BinaxNOW S. pneumoniae urinary antigen test, Gram stain, culture and lytA PCR were performed on all samples. Diagnostic accuracy of the antigen test and Gram stain with gram-positive cocci in pairs were compared with culture, polymerase chain reaction (PCR) and the composite of culture and PCR. Results: Streptococcus pneumoniae was isolated in 26% of samples, 66% cultured other gram-positive organisms and 8% of samples had no growth. Sensitivity and negative predictive values of the antigen test were 100%, specificity and positive predictive values were 87% – 88% and 76% – 81%, but increased to 93% – 96% and 96% – 98% when applied to subsets with gram-positive cocci in pairs, or history compatible with respiratory illness or meningitis. Sensitivity (69% – 75%) and specificity (81%) of Gram stain (gram-positive cocci in pairs) were lower than the antigen test even when applied to the same subsets. Conclusion: Accurate and rapid diagnosis of S. pneumoniae bacteraemia is challenging. Specificity of this antigen test is limited by cross-reactivity with other gram-positive organisms, but could be improved if Gram stain morphology and clinical history are available. The antigen test is a useful adjunct for rapid diagnosis of S. pneumoniae bacteraemia.https://sajid.co.za/index.php/sajid/article/view/244streptococcus pneumoniaebacteraemiabinaxnowantigenpneumococcal diagnosistest |
| spellingShingle | Hafsah D. Tootla Colleen Bamford Chad M. Centner Clinton Moodley The BinaxNOW pneumococcal antigen test: An adjunct for diagnosis of pneumococcal bacteraemia Southern African Journal of Infectious Diseases streptococcus pneumoniae bacteraemia binaxnow antigen pneumococcal diagnosis test |
| title | The BinaxNOW pneumococcal antigen test: An adjunct for diagnosis of pneumococcal bacteraemia |
| title_full | The BinaxNOW pneumococcal antigen test: An adjunct for diagnosis of pneumococcal bacteraemia |
| title_fullStr | The BinaxNOW pneumococcal antigen test: An adjunct for diagnosis of pneumococcal bacteraemia |
| title_full_unstemmed | The BinaxNOW pneumococcal antigen test: An adjunct for diagnosis of pneumococcal bacteraemia |
| title_short | The BinaxNOW pneumococcal antigen test: An adjunct for diagnosis of pneumococcal bacteraemia |
| title_sort | binaxnow pneumococcal antigen test an adjunct for diagnosis of pneumococcal bacteraemia |
| topic | streptococcus pneumoniae bacteraemia binaxnow antigen pneumococcal diagnosis test |
| url | https://sajid.co.za/index.php/sajid/article/view/244 |
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