A selective culture medium for screening linezolid-resistant gram-positive bacteria.

The SuperLinezolid medium was developed for screening resistance to linezolid (LZD) in Gram-positive bacteria (Staphylococcus spp., Enterococcus spp.). It was evaluated using LZD-susceptible (n = 20) and LZD-resistant (n = 17) Gram-positive isolates. The sensitivity was found to be 82% at 24 h (3 out of 17 isolates being missed), and reached 100% at 48 h. At 48 h, a single LZD-susceptible isolate grew (specificity 95%). By testing stools spiked with LZD-resistant Gram-positive strains, an excellent performance of the medium was observed, with a lowest detection limit ranging from 101 to 102 CFU/ml. Overall, this medium is accurate for detection of LZD-resistant Gram-positive isolates after 24 h of culture.