The invention relates to nitrogen-containing heterocyclic compounds of general formula (I) wherein: R1 represents a (CH2)n—NH2 radical, n being equal to 1 or 2; R2 represents a hydrogen atom; R3 and R4 form together a nitrogen-containing heterocycle with aromaticity with 5 apices containing 1, 2 or 3 nitrogen atoms, substituted on this nitrogen atom or one of these nitrogen atoms with a (CH2)m—(C(O))p—R5 group, m being equal to 0, 1, 2 or 3, p being equal to 0 or 1 and R5 representing a hydroxy group, in which case p is equal to 1, or an amino, (C1-C6)alkyl or di-(C1-C6)alkyl amino, a nitrogen-containing heterocycle with aromaticity with 5 or 6 apices containing 1 or 2 nitrogen atoms and if necessary, an oxygen or sulfur atom; it being understood that when the sub-group (C(O))p—R5 forms a carboxy, amino, (C1-C6) alkyl or di-(C1-C6) alkyl amino, group, m is different from 0 or 1; in free form or as zwitterions and salts with pharmaceutically acceptable mineral or organic bases and acids, to their preparation and to their use as antibacterial drugs.