 Linezolid has no clinically significant effect on most Gram @-@ negative bacteria . Pseudomonas and the Enterobacteriaceae , for instance , are not susceptible . In vitro , it is active against Pasteurella multocida , Fusobacterium , Moraxella catarrhalis , Legionella , Bordetella , and Elizabethkingia meningoseptica , and moderately active ( having a minimum inhibitory concentration for 90 % of strains of 8 mg / L ) against Haemophilus influenzae . It has also been used to great effect as a second @-@ line treatment for Capnocytophaga infections . 
