| 摘要 |
beta -lactam antibiotics of formula (I) or a salt thereof: wherein X is hydrogen or a group NHR<1>, wherein R<1> is hydrogen or an amino protecting group, and R is an optionally substituted spiro, fused or bridged bicyclic or tricyclic group optionally containing one or more heteroatoms selected from oxygen, nitrogen and sulphur, useful in the treatment of bacterial infections in humans and animals. |
