Comparison of an Automated Plate Assessment System (APAS Independence) and Artificial Intelligence (AI) to manual Plate Reading of Methicillin-resistant and Methicillin-susceptible Staphylococcus aureus Chromagar Surveillance Cultures

The APAS Independence is an automated imaging station linked with interpretive software that detects target colonies of interest on chromogenic media and sorts samples as negative or presumptive positive. The study evaluated the accuracy of the APAS Independence to triage methicillin-resistant Staphylococcus aureus (MRSA) and S. aureus) cultures using chromogenic media compared to human interpretation.

Samples were analysed by APAS Independence before being read by a trained technologist who was blinded to the APAS Independence interpretation. The triaging by both APAS Independence and the technologists were compared for accuracy. Any discordant results required further analysis by a third reader.

A total of 5,913 CHROMagar MRSA cultures were evaluated and 236 were read as concordantly positive, 5,525 were read as concordantly negative, and 152 required discordant analysis. Positive and negative percent agreements (PPA, NPA) were 100% and 97.3%, respectively. The APAS Independence detected 5 positive cultures that were missed by manual reading and determined to be true positives.

In a separate analysis, 744 CHROMagar Staph aureus plates were read in parallel. Of these, 133 were concordantly positive, 585 were concordantly negative, and 26 required discordant analysis. PPA and NPA were 95.7% and 96.7%, respectively.

This study confirmed the high sensitivity (Negative Predictive Value (NPV) 100% for CHROMagar MRSA and 99.0% for CHROMagar Staph aureus) of digital image analysis by the APAS Independence such that negative cultures can be reliably reported without technologist intervention.

Journal: Journal of clinical Microbiology

Date: August 2021

Authors: Gammel N, Ross T.L, Lewis S, Oslon M, Henciak S, Harris R, Hanlon A, Carroll K.C.

Citation: Gammel N, Ross TL, Lewis S, Olson M, Henciak S, Harris R, Hanlon A, Carroll KC. Comparison of an Automated Plate Assessment System (APAS Independence) and Artificial Intelligence (AI) to Manual Plate Reading of Methicillin-resistant and Methicillin-susceptible Staphylococcus aureus Chromagar Surveillance Cultures. J Clin Microbiol. 2021 Aug 11:JCM0097121.

doi: 10.1128/JCM.00971-21 

 

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