Ultrastructure and viability of E. coli treated fosfomycin.

In concentrations of 6 microgram/ml Fosfomycin acted bactericidal against E. coli ATCC 10536. The sensitivity of E. coli was evaluated by turbidity measurement (Table 1) and by counting colony forming units (CFU) (Table 2). Thus the bactericidal action began at different times in respect to the concentration and the method of documentation: turbidity fell 30-120 min after the administration of 6 microgram/ml and 10-30 min after 60 microgram/ml; CFU were reduced 10-30 min after 6 microgram/ml and 3-10 min after 60 microgram/ml. Before the cytoplasm and DNA-region were disorganized with reduced electron density, some elongated (up to more than 20 micron) cells occurred (Fig. 1,2). More prominent alterations in shape and ultrastructure were obvious 120 min after 6 microgram/ml (Fig. 5) and after 30 min when 60 microgram Fosfomycin per ml were administered (Fig. 3, 4), i.e. considerably later than the reduction of reproductivity.