Hepatitis testing update.

During a 25-year period, four types of hepatitis-causing virus have been identified and can now be evaluated serologically. This final article in this clinical laboratory medicine series reviews routes of virus transmission and persistence and the availability of tests.

Group A Streptococcus detection: office versus reference laboratory.

Clinical differentiation between a virus and beta-hemolytic streptococci as a cause of pharyngitis remains difficult. In the physician's laboratory, more rapid procedures using immunologic methods have replaced culture methods, traditionally requiring 2 to 3 days for identification of beta-hemolytic streptococci. Attention to the diagnostic sensitivity and specificity of these procedures will guide appropriate use.