1. A compound of formula (I) or a stereoisomer thereof, or a pharmaceutically acceptable salt thereof, wherein M is kation.2. A compound according to Claim. 1, where M is hydrogen, sodium or kaliy.3. A pharmaceutical composition for treating bacterial infections comprising a compound according to Claim. 1 or 2.4. A method for preventing or treating a bacterial infection in a subject comprising administering to said subject a pharmaceutically effective amount of a compound according to Claim. 1 or 2.5. A method for preventing or treating a bacterial infection in a subject, wherein said infection is caused by a bacterium, producing one or more beta-lactamase enzyme, wherein said method comprises administering to said subject a pharmaceutically effective amount of a compound according to Claim. 1 or 2.6. A method for preventing or treating a bacterial infection in a subject comprising administering to said subject a pharmaceutically effective amount of para. 3.7 pharmaceutical composition. A method for preventing or treating a bacterial infection of the subject, wherein said infection is caused by a bacterium, producing one or more beta-lactamase enzyme, wherein said method comprises administering to said subject a pharmaceutically effective amount of a pharmaceutical composition according to claim. 3.8. A pharmaceutical composition according to claim. 3, comprising, in addition, at least one antibacterial agent or a pharmaceutically acceptable sol.9. A method for preventing or treating a bacterial infection in a subject comprising administering to said subject a pharmaceutically effective amount of: (a) a compound of formula (I) according to claim 1, or a stereoisomer, or a pharmaceutically.1. Соединение формулы (I)или его стереоизомер, или его фармацевтически приемлемая соль, где М означает катион.2. Соединение по п. 1, где М означает водород, натрий или калий.3. Фармацевтическая композиция для лечения бактериальной инфекции, содержащая соединение по п. 1 или 2.4. Сп
