Verification of the BIOMIC® at the Wisconsin State Laboratory of Hygiene

This capstone project involved the verification of computer software for an instrument called the BIOMIC® at the Wisconsin State Laboratory of Hygiene in the Communicable Diseases Division. The BIOMIC® is used daily to read antimicrobial susceptibility results for different groups of organisms, including enteric bacteria like Salmonella and Shigella, S. pneumoniae, and a variety of carbapenem-resistant Gram-negative bacteria. Additionally, the instrument reads a panel that is used to identify Enterobacterales and other non-fastidious, Gram-negative bacteria. The machine is an essential piece of surveillance equipment for providing updates on emerging antimicrobial resistance in bacteria species from Wisconsin and other states.

The problem addressed in this project was that a software update needed verification to bring the latest version of the BIOMIC® online. The BIOMIC® verification process involved subculturing stored specimens from the WSLH’s collection and using them to prepare AST plates. The 96-well AST plates were prefilled with lyophilized antimicrobics at the bottom of each well. A bacterial suspension in nutrient broth was added to rehydrate the antimicrobial agents and the plate was incubated overnight. The following day, the BIOMIC® read the minimum inhibitory concentrations (MICs) on the AST plates and provided an interpretation, classifying a strain as either susceptible, intermediate, or resistant to a certain antimicrobic. These interpretations were compared to those found in the Clinical and Laboratory Standards Institute’s (CLSI’s) document called the M100 Performance Standards for Antimicrobial Susceptibility Testing. An agreement between the BIOMIC® reads and the CLSI’s standards ensured that the new software was performing the analyses correctly. The goal was to have the new BIOMIC® software analyze the MICs correctly for the AST panels and to interpret the results with 100% agreement with the CLSI standards. The result components were checked for the instrument’s most common assays.