MicroScan Dried Gram-Negative MIC/Combo Panels with Aztreonam (AZT) (0.5-64 µg/mL)

The MicroScan Dried Gram-Negative MIC/Combo Panel with Aztreonam is a laboratory test system that determines antimicrobial susceptibility of gram-negative bacteria by measuring minimum inhibitory concentration (MIC) of aztreonam. Isolated colonies are inoculated onto dried microdilution panels containing aztreonam at concentrations of 0.5–64 µg/mL, incubated overnight at 35°C, and read either manually or with automated instruments to report susceptibility for Enterobacterales and Pseudomonas aeruginosa.

The device uses miniaturized broth microdilution methodology with dehydrated antimicrobial agents. It is nearly identical to the predicate device in technology, specimen type, incubation parameters (35°C ± 1°C, aerobic, 16–20 hours), and reading methods (automated or manual). The sole technical difference is substitution of aztreonam as the antimicrobial agent instead of ceftazidime, both at identical concentration ranges (0.5–64 µg/mL).

The submission references the FDA document 'Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA' (August 28, 2009) and comparison with CLSI frozen Reference Panels as the validation standard.

Substantial equivalence is established because aztreonam and ceftazidime are both beta-lactam antimicrobials used to test the same bacterial species, the platform technology and all operational parameters are identical to the predicate, and performance data demonstrate acceptable agreement with CLSI reference standards (Enterobacterales: 91.0% essential agreement, 93.1% categorical agreement; Pseudomonas aeruginosa: 91.2% essential agreement, 86.0% categorical agreement). Reproducibility and quality control testing also met acceptable criteria, showing the new antimicrobial agent performs equivalently within the established system.