[Fosfomycin, a new antibiotic: in vitro activity compared with mezlocillin, cefuroxime and gentamicin]

In vitro investigations with fosfomycin, mezlocillin, cefuroxime, and gentamicin against staphylococci, enterobacteriaceae an pseudomonadaceae were carried out by Agar Dilution method on Mueller-Hinton agar. The fosfomycin breakpoint for the low dosage of 2-3 times 3 g per infusion daily was defined with 16 micro g/ml and for the high dosage of 2-3 times 5 g fosfomycin per infusion with 64 micro g/ml. At a concentration of 16 micro g/l fosfomycin more than 90% of the cultures of staph. aureus (penicillin-resistant), e. coli, proteus mirabilis an proteus vulgaris examined were inhibited. At a concentration of less than 64 micro g/ml fosfomycin 80 toi 100% of the cultures of serratia marcescens, klebsiella pneumoniae, enterobacter cloacae, proteus morgani et rettgeri and pseudomonas aeruginosa (gentamicin sensitive and resistant) were inhibited. Fosfomycin showed an absolute stability against many Beta-Lactamases of different bacterial species.