Role of rapid tests for streptococcal pharyngitis in hospital infection control.

Rapid streptococcal antigen detection tests are now an alternative to throat cultures for diagnosing group A streptococcal pharyngitis. Used alone, they are not suitable for hospital infection control applications because of the risk that individuals with streptococcal pharyngitis and a falsely negative test will spread the infection within the institution. However, a rapid test may be an economical method for screening employees with pharyngitis, provided that a throat culture is performed for everyone with a negative test. Compared with the use of throat cultures alone, this strategy reduces the number of missed diagnoses and the number of work days lost. Cost-benefit analysis shows that over a wide range of streptococcal prevalence and carrier rate the total cost is also less with the use of rapid tests first. If the prevalence of streptococcal pharyngitis is very low, the use of cultures alone is more cost-effective.