Detection of Group A Streptococci in the Laboratory or Physician's Office

Abstract

Much controversy has existed concerning the clinical significance of small numbers of group A streptococci (eg, one to ten or even 50 colonies) recovered in culture. The relative quantity of streptococci recovered is, in part, technique dependent. This review documents the need for sensitive throat culture technology, addresses technical problems associated with the culture procedure, and, in light of these problems, explores the need for very carefully performed studies on streptococcal antigen detection kits before their implementation as a routine test either in physicians' offices or in microbiology laboratories.

Does near-to-patient testing contribute to the diagnosis of streptococcal pharyngitis in adults?

“…This method has its own potential errors, however, since it sometimes misses streptococcal infections (2). In the present study, 10 patients with a negative culture, but with a four-fold.…”

“…The differential diagnosis of throat infections constitutes a major challenge to the clinician. By evaluating symptoms and signs it is difficult to establish an aetiologic diagnosis; this is best done by microbiological culture (2). Culture, however, is often of limited practical value because the results are first available after 24 hours.…”

Evaluation of the Directigen 1,2,3 Group A Strep Test for diagnosis of streptococcal pharyngitis

“…Recently, antigen detection methods have become sufficiently sensitive to detect group A streptococcal (GAS) antigens extracted directly from throat swabs (1-4, 7, 8). As commercial products for the direct rapid detection of GAS have become available, the diagnosis of streptococcal pharyngitis has shifted from the microbiology laboratory to the physician's office (6,10,11).…”