The procedure of direct susceptibility testing of pathogens from positive blood cultures with the MICRONAUT system was evaluated externally by using the culture flasks PLUS Aerobic/F, PLUS Anaerobic/F, and PLUS Pediatric.

For direct susceptibility testing with the MICRONAUT system, 8 ml of the positive blood culture medium is centrifuged at 800 rpm for 10 min.

The supernatant is transferred into a new tube and centrifuged at 3,000 rpm for 5 min. and the resulting pellet is diluted in sterile 0.9% saline to prepare a 0.5-McFarland-standard suspension.

This suspension is then inoculated according to the instructions for the MICRONAUT system for antimicrobial susceptibility testing.

Reference:
Evaluation of the Merlin MICRONAUT System for Rapid Direct Susceptibility Testing of Gram-Positive Cocci and Gram-Negative Bacilli from Positive Blood Cultures.

Nele Wellinghausen et al., Journal of Clinical Microbiology 45: 789 -795 (2007)