Diagnosis of group A streptococcal pharyngitis in a private clinic: comparative evaluation of an optical immunoassay method and culture.

We compared the sensitivity and specificity of the Strep A Optical ImmunoAssay (OIA) method with our routine trypticase soy agar with 5% sheep blood (TSA) culture technique and with a broth-enhanced culture in the diagnosis of group A beta-hemolytic streptococcal infection. Compared with broth-enhanced culture, the Strep A OIA had a sensitivity and specificity of 94.8% and 98.8%, respectively; TSA culture had a sensitivity and specificity of 92.5% and 99.4%, respectively. The Strep A OIA, which takes 10 minutes to perform, offered sensitivity and specificity equivalent to that of TSA culture in the diagnosis of group A beta-hemolytic streptococcal pharyngitis.