Activity of FL 1060, a new beta-lactam antibiotic, against urinary tract pathogens.

The effect of the new beta-lactam antibiotic FL 1060 on urinary tract pathogens, of which 71 were sensitive to and 100 resistant to ampicillin, is presented here. When tested by conventional methods FL 1060 was found to be highly active against ampicillin-sensitive strains of E. coli but phenotypically resistant variants readily emerged, particularly when a large inoculum was used. Thirty-one per cent of ampicillin-resistant strains were found to be sensitive to less than 500 mug FL 1060 per ml, and in general this antibiotic was more active than ampicillin against resistant strains. In a system simulating the mechanical features of the urinary bladder the activity of FL 1060 against three sensitive strains of E. coli was found to be greater than ampicillin in conditions of low, but not high, osmolality.