Abstract
Throat swabs from 196 pediatric patients were processed by a direct extraction-latex agglutination method (Group A Strep Direct Antigen Identification Test [DAI]) that detects group A streptococci in the specimen. The method requires a 45-min enzymatic extraction period at 37 degrees C and a 4-min reaction period with antibody-linked latex particles. The results were compared with those of the culture and fluorescent antibody methods and the clinical presentation of the patient for pharyngitis. Ninety-three percent of the specimens resulted in agreement by all tests, and 28% were culture positive for group A streptococci. Compared with the culture method, the DAI had a sensitivity and a specificity of 83% and 99%, respectively. The positive predictive values were 98% versus the culture method and 93% versus the fluorescent antibody method, whereas the negative predictive values were 94% versus both other methods. Of the 14 discrepant results when both clinical presentation of an acute pharyngitis and the test results were compared, the culture method provided the best correlation. An additional 64 specimens were processed by the DAI and another direct extraction-latex agglutination method (Culturette Ten-Minute Group A Strep ID Test), and the results were compared with those of the culture method. This group had a 40.6% culture isolation rate for group A streptococci. The sensitivity and specificity of the DAI and Strep ID methods versus the culture method were 81 and 100%, and 77 and 97%, respectively. These results indicate that the DAI is accurate for diagnosing group A streptococcal pharyngitis directly from throat swabs. However, negative results in the presence of a symptomatic patient must be confirmed by standard culture techniques.
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Selected References
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- Arthur J. D., Bass J. W., York W. B. How is suspected streptococcal pharyngitis managed?. A study of what physicians actually think and do. Postgrad Med. 1984 Mar;75(4):241, 244-5, 248. doi: 10.1080/00325481.1984.11697969. [DOI] [PubMed] [Google Scholar]
- Ferrieri P., Blair L. L. Pharyngeal carriage of group B streptococci: detection by three methods. J Clin Microbiol. 1977 Aug;6(2):136–139. doi: 10.1128/jcm.6.2.136-139.1977. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Funamura J. L., Berkowitz C. D. Applicability of a scoring system in the diagnosis of streptococcal pharyngitis. Clin Pediatr (Phila) 1983 Sep;22(9):622–626. doi: 10.1177/000992288302200906. [DOI] [PubMed] [Google Scholar]
- Glass R., Fischer Z., Bottone E. J. Inaccuracy of house staff in reading throat cultures. JAMA. 1978 Dec 8;240(24):2651–2652. [PubMed] [Google Scholar]
- Griner P. F., Mayewski R. J., Mushlin A. I., Greenland P. Selection and interpretation of diagnostic tests and procedures. Principles and applications. Ann Intern Med. 1981 Apr;94(4 Pt 2):557–592. [PubMed] [Google Scholar]
- Holmberg S. D., Faich G. A. Streptococcal pharyngitis and acute rheumatic fever in Rhode Island. JAMA. 1983 Nov 4;250(17):2307–2312. [PubMed] [Google Scholar]
- Otero J. R., Reyes S., Noriega A. R. Rapid diagnosis of group A streptococcal antigen extracted directly from swabs by an enzymatic procedure and used to detect pharyngitis. J Clin Microbiol. 1983 Aug;18(2):318–320. doi: 10.1128/jcm.18.2.318-320.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Peter G., Smith A. L. Group A streptococcal infections of the skin and pharynx (second of two parts). N Engl J Med. 1977 Aug 18;297(7):365–370. doi: 10.1056/NEJM197708182970706. [DOI] [PubMed] [Google Scholar]
- Slifkin M., Gil G. M. Evaluation of the Culturette Brand Ten-Minute Group A Strep ID technique. J Clin Microbiol. 1984 Jul;20(1):12–14. doi: 10.1128/jcm.20.1.12-14.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]