Rapid detection of group A streptococcal antigen for the clinician and the epidemiologist: accurate? cost-effective? useful?

Reviewing the literature describing rapid antigen detection for the diagnosis of group A streptococcal upper respiratory tract infections, one can conclude that the rapid aspect of these tests is clearly advantageous. To be able to have an answer in 5-20 minutes has distinct advantages with regard to therapy for patients. The specificity of most of these tests is acceptable for group A streptococci, although one must recognise that group C and group G streptococci can cause upper respiratory tract infection, and would not be detected by any group A antigen test. A remaining problem appears to be that of sensitivity. Although the range of sensitivity with various techniques and in the hands of different investigators may vary, it is difficult to ignore the fact that the sensitivity for many tests does not appear to be optimal. Furthermore, appropriate technical skill is required before these tests can be recommended for use in the hands of inadequately trained individuals, either in an office laboratory or in peripheral health care stations. There is also the concern that the cost for these diagnostic tests, unless purchased in large quantities, generally is greater than for the throat culture. This could have significant implications in some health care situations. One potential alternative for the office practitioner to consider is that if a rapid antigen test is negative, he or she should also perform a throat culture. This is the routine carried out in many practising clinicians' offices.(ABSTRACT TRUNCATED AT 250 WORDS)