The comparative activity of fosfomycin trometamol against organisms isolated from infected urines.

Five hundred urinary pathogens, collected from patients of general practitioners and hospital in-patients, were identified and tested for susceptibility to fosfomycin, ampicillin, cephalexin, nalidixic acid, nitrofurantoin, trimethoprim and sulfamethoxazole. Overall, 83% of the isolates were sensitive to fosfomycin, comprising 89% of the out-patient strains and 77% of the in-patient isolates. This degree of sensitivity was similar to that of cephalexin, nalidixic acid and trimethoprim, but higher than that observed with ampicillin, nitrofurantoin and sulfamethoxazole. Fosfomycin generally showed a broad spectrum of activity, but was less active than some other compounds against Klebsiella spp. and streptococci. More than 70% of strains resistant to ampicillin, sulfamethoxazole or trimethoprim were sensitive to fosfomycin indicating that cross resistance is not presently a problem.