The present invention addresses the problem of providing a compound and pharmaceutical composition which have strong antibacterial activity against gram-negative bacteria and drug-resistant strains thereof. The compound according to the present invention represented by general formula [1], where each symbol is as defined in the description, or a salt of said compound, has strong antibacterial activity against gram-negative bacteria such as Pseudomonas aeruginosa, and drug-resistant strains thereof such as multidrug-resistant Pseudomonas aeruginosa. A pharmaceutical composition containing the composition or a salt thereof is useful as an antibacterial agent.本發明的課題為提供一種對於革蘭氏陰性菌及該等的藥劑耐性菌顯示出強的抗菌活性之化合物及醫藥組成物。依本發明，通式[1]所表示之化合物或其鹽對於以綠膿桿菌為代表之革蘭氏陰性菌及包括多藥耐性綠膿桿菌之該等的藥劑耐性菌具有強的抗菌活性，含有該等之醫藥組成物作為抗菌劑而有用，式中，各記號如說明書所記載。
