Disclosed is a medicament having a strong antibacterial activity against Gram-positive bacteria, Gram-negative bacteria, and resistant bacteria. A compound represented by formula [I] or a salt thereof is useful as an antibacterial agent. In formula [I], a bond containing a dotted line and connecting X2 to Y1 represents a single bond or a double bond Z1, Z2, Z3, Z4, Z5, and Z6 each represent a nitrogen atom, formula: CH, or the like X1 represents a C1-4 alkylene group which may be substituted by an oxo group X2 represents a bonding hand or formula: CH Y1 represents a spirocyclic group selected from a group of formulae (II) X3 represents a C1-4 alkylene group, formula: NR10(CH2)m, formula: SOn, or a bonding hand and R7 represents a C3-6 cycloalkyl group, a C3-6 cycloalkenyl group, an aryl group, a monocyclic heterocyclic group, a bicyclic heterocyclic group, or the like.本發明係關於提供一種對革氏陽性菌、革氏陰性菌及耐性菌具有強抗菌活性的藥劑。式[I]式[I]所示化合物或其鹽可作為抗菌劑使用。(式中,含有連結X2與Y1的點線之鍵結表示單鍵或雙鍵,Z1、Z2、Z3、Z4、Z5、Z6表示氮原子或式CH等,X1表示可由側氧基取代之C1-4伸烷基,X2表示鍵結鍵或式CH,Y1表示選自式群(II)的螺環基等,X3表示C1-4伸烷基、式NR10(CH2)m、式SOn或鍵結鍵,R7表示C3-6環烷基、C3-6環烯基、芳基、單環雜環基或二環雜環基等)。
