Digital Detection of Group A Streptococcus using Colorex Strep A CHROMagar and WASPLab Chromogenic Detection Module

Despite the availability of several diagnostics tools for the diagnosis of Group A Streptococcus (GAS) pharyngitis, culture remains one of the primary methods in use today and is still considered the gold standard for the detection of GAS from pharyngeal samples. This is likely because culture has high sensitivity compared to rapid antigen tests and low cost compared to molecular approaches. However, in larger volume laboratories, screening for GAS by culture can be cumbersome and streamlined approaches using automated plating instrumentation, smart incubation and image analysis could be helpful.

This study evaluates the capability of the WASPLab® Total Laboratory Automation System (TLA) (Figure 1) (Copan Diagnostics, Murrieta, CA) PHENOMatrix™ Chromogenic Detection Module (CDM) to automatically detect and interpret orange GAS colonies on a novel chromogenic agar called Colorex Strep A Agar (CHROMagar, Paris, France). To date the Colorex Strep A Agar is not Food and Drug Administration (FDA) cleared.