| abstract |
Cephalosporin derivatives effective against gram-negative bacteria and virtually inactive against staphylococci are disclosed. The derivatives have the following general formula: <IMAGE> in which R is <IMAGE> R'' and R''' are hydrogen, lower alkyl or together are 1,3-propylene or 1,4-butylene, and X and X' are hydrogen, cation or easily metabolically labile and pharmaceutically acceptable ester or hemiacetal. |