[In vitro effect of fosfomycin against Pseudomonas aeruginosa compared to carbenicillin, gentamycin and polymyxin B]

Abstract

The activity of fosfomycin against Pseudomonas aeruginosa (78 serotyped strains isolated from clinical specimens) is considerably more dependent on test conditions than that of carbenicillin, polymyxin B or gentamicin. Using a degree of standardization of the micro-serial dilution test and agar diffusion test (Iso-Sensitest broth and agar), which yields a high degree of correlation between the values of both techniques with carbenicillin and gentamicin, a moderate degree of correlation is obtained with fosfomycin. In regard to minimal inhibitory concentration (MIC) values in human serum and human urine, fewer "false" results are obtained in Iso-Sensitest broth than in Mueller Hinton broth and in particular glucose caseinhydrolysate broth. On the basis of MIC values in Iso-Sensitest broth P. aeruginosa is much more sensitive to polymyxin B, carbenicillin and gentamicin than to fosfomycin.