We evaluated the Solana Group A Streptococcus Assay (Quidel, San Diego, CA), a nucleic acid amplification test (NAAT), as a substitute for backup culture on throat specimens with a negative rapid group A Streptococcus (GAS) antigen assay.
During October 2016, all throat swabs from patients with a negative GAS antigen assay from local urgent care centers were processed by NAAT and conventional culture in real time.
The overall agreement of the 2,090 tested throat swab specimens of the NAAT with the culture was 2,050 (98%) of 2,090. Sensitivity, specificity, positive predictive value, and negative predictive value were 91.4%, 98.5%, 78.0%, and 99.5%, respectively.
In summary, this postimplementation study supported high sensitivity and specificity of the GAS NAAT as a backup test for negative rapid GAS antigen tests.