The invention relates to antibacterial compounds of formula (I), wherein R1 is H, halogen, (C1-C3)alkyl or (C1-C3)alkoxy; R2 is H, halogen, (C1-C3)alkyl, (C1-C3)alkoxy or pyrrolidin-1-yl; R3 is H, halogen, (C1-C3)alkyl, (C1-C3)alkoxy, vinyl or 2-methoxycarbonyvinyl or R2 and R3 together with the two carbon atoms which bear them form a phenyl ring; R4 is H, halogen, (C1-C3)alkyl or (C1-C3)alkoxy; and R5 is H, (C1-C3)alkyl or cyclopropyl, or R4 and R5form together a —CH2CH2CH2— group; A is the divalent group —CH2—, —CH2CH2—, #—CH(OH)CH2—*, #—CH2N(R6)—* and —CH2NHCH2—, wherein # indicates the point of attachment to the optionally substituted (quinazoline-2,4-dione-3-yl)methyl residue and * represents the point of attachment to the substituted (oxazolidinon-4-yl)methyl residue; R6 is H or acetyl; Y is CH or N; and Q is O or S; and salts of such compounds.