Susceptibility to Phosphomycin as a Differential Character for Gram Negative Anaerobic Bacilli

Abstract
On the basis of their sensitivity to phosphomycin, various species of anaerobic Gram negative bacilli examined fell into one of two groups. All strains of Bacteroides were resistant to 500 umg/ml whereas strains of Fusobacterium were uniformly sensitive to 62.5 μg/ml. Disc sensitivity testing to phosphomycin at concentrations of 200–500 μg/ml provides a reliable and rapid means of distinguishing fusobacteria from bacteroides.