Susceptibility testing quality control studies with fosfomycin tromethamine.

Multiple studies were performed to define the quality control ranges for susceptibility tests of fosfomycin tromethamine. For disk diffusion tests, the limits proposed are 22 to 30 mm for Escherichia coli ATCC 25922 and 25 to 33 mm for Staphylococcus aureus ATCC 25923. Broth microdilution tests were not reproducible. For agar dilution tests, ranges proposed are 0.5 to 2.0 micrograms/ml for Escherichia coli ATCC 25922, 0.5 to 4.0 micrograms/ml for Staphylococcus aureus ATCC 29213; 2.0 to 8.0 micrograms/ml for Pseudomonas aeruginosa ATCC 27853, and 32 to 128 micrograms/ml for Enterococcus faecalis ATCC 29212.