Skip to main content
NCBI home page
Journal of Clinical Microbiology logoLink to Journal of Clinical Microbiology
. 1992 Aug;30(8):2135–2138. doi: 10.1128/jcm.30.8.2135-2138.1992

Comparison of three methods for detection of group A streptococci in throat swabs.

J P Anhalt 1, B J Heiter 1, D W Naumovitz 1, P P Bourbeau 1
PMCID: PMC265457  PMID: 1500522

Abstract

Group A streptococci are generally detected in throat swabs by (i) rapid antigen tests, (ii) conventional culture, or (iii) combinations of both. Direct fluorescent-antibody testing of a 2-h enrichment broth (FA/EN) was an accepted method for same-day results before the advent of rapid antigen tests. We compared FA/EN in Todd-Hewitt Broth (THB) with conventional culture and a rapid antigen test, TestPack Strep A (TPS). Nine hundred seventy specimens were evaluated in this study. Cultures were performed for 48 h on sheep blood agar (SBA) incubated aerobically and on a selective agar for group A streptococci (SSA) incubated in 5 to 10% CO2. Following a 2-h incubation, the fluorescent-antibody test was performed. A subculture of the centrifuged sediment from the THB enrichment was also done. In comparison with a positive culture on SBA or SSA or subculture of the THB pellet, the sensitivities and specificities of the different methods were as follows: SBA, 92 and 100%; SSA, 92 and 100%; TPS, 68 and 99%; FA/EN, 88 and 98%. The FA/EN method offers the potential for definitive finalized reports on the same day as specimen collection with greater sensitivity than TPS. This study included sequential plating and rapid antigen testing of a single swab. In a separate set of experiments to validate this study design, it was shown that recovery of streptococci from swabs plated sequentially on five plates did not vary with the order of plating and the actual proportion of organisms recovered from a swab on a single plate was only 1%.

Full text

PDF
2135

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bisno A. L. Group A streptococcal infections and acute rheumatic fever. N Engl J Med. 1991 Sep 12;325(11):783–793. doi: 10.1056/NEJM199109123251106. [DOI] [PubMed] [Google Scholar]
  2. CHERRYWBMOODY M. D. FLUORESCENT-ANTIBODY TECHNIQUES IN DIAGNOSTIC BACTERIOLOGY. Bacteriol Rev. 1965 Jun;29:222–250. [PMC free article] [PubMed] [Google Scholar]
  3. Dobkin D., Shulman S. T. Evaluation of an ELISA for group A streptococcal antigen for diagnosis of pharyngitis. J Pediatr. 1987 Apr;110(4):566–569. doi: 10.1016/s0022-3476(87)80550-4. [DOI] [PubMed] [Google Scholar]
  4. Gerber M. A. Culturing of throat swabs: end of an era? J Pediatr. 1985 Jul;107(1):85–88. doi: 10.1016/s0022-3476(85)80620-x. [DOI] [PubMed] [Google Scholar]
  5. Ilstrup D. M. Statistical methods in microbiology. Clin Microbiol Rev. 1990 Jul;3(3):219–226. doi: 10.1128/cmr.3.3.219. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Kaplan E. L. The rapid identification of group A beta-hemolytic streptococci in the upper respiratory tract. Current status. Pediatr Clin North Am. 1988 Jun;35(3):535–542. doi: 10.1016/s0031-3955(16)36470-7. [DOI] [PubMed] [Google Scholar]
  7. Kellogg J. A., Bankert D. A., Levisky J. S. Comparison of the TestPack Strep A enzyme immunoassay system with anaerobically incubated cultures for detection of group A streptococci from oropharyngeal swabs. Am J Clin Pathol. 1987 Nov;88(5):631–634. doi: 10.1093/ajcp/88.5.631. [DOI] [PubMed] [Google Scholar]
  8. Kellogg J. A., Landis R. C., Nussbaum A. S., Bankert D. A. Performance of an enzyme immunoassay test and anaerobic culture for detection of group A streptococci in a pediatric practice versus a hospital laboratory. J Pediatr. 1987 Jul;111(1):18–21. doi: 10.1016/s0022-3476(87)80335-9. [DOI] [PubMed] [Google Scholar]
  9. Kellogg J. A. Suitability of throat culture procedures for detection of group A streptococci and as reference standards for evaluation of streptococcal antigen detection kits. J Clin Microbiol. 1990 Feb;28(2):165–169. doi: 10.1128/jcm.28.2.165-169.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Schwabe L. D., Small M. T., Randall E. L. Comparison of TestPack Strep A test kit with culture technique for detection of group A streptococci. J Clin Microbiol. 1987 Feb;25(2):309–311. doi: 10.1128/jcm.25.2.309-311.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Waters C. A., Makens M. A. Rapid fluorescent-antibody method with bromelase for identification of group A streptococci. J Clin Microbiol. 1977 Feb;5(2):255–256. doi: 10.1128/jcm.5.2.255-256.1977. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Journal of Clinical Microbiology are provided here courtesy of American Society for Microbiology (ASM)

RESOURCES