The invention relates to nitrogenous heterocyclic compounds of the formula (I) where: R1 is hydrogen, -(CH2)m-NH2, -(CH2)m-NH(C1-C6)alc, -(CH2)m-N(C1-C6)alc2, - (CH2)m-NH-C(NH)NH2 or -(CH2)m-NH-CH=NH, m being equal to 1 or 2 R2 and R3 together form an aromatic nitrogenous heterocycle with 5 vertexes including 1, 2 or 3 nitrogen atoms, substituted by R4 on a nitrogen atom R4 is hydrogen, (C1-C6)alc or a chain of the formula -(A)n-(NH)0-(CH2)p-(CHR)q R" A is C=O, C=NH or SO2 R is hydrogen or carboxy R" is hydrogen, NH2, NH(C1-C6)alc, N(C1-C6)aIc2, CONH2, CONH(C1 -C6)alc, CON(C1-C6)alc2, or a saturated heterocycle with 5 or 6 vertexes including 1 or 2 nitrogen atoms and optionally an oxygen or sulphur atom bonded to the chain by a nitrogen or carbon atom and optionally substituted by (C1-C6)alc n, o and q are 0 or 1 and p is an integer from 0 to 4 R5 is OSO3H, OCFCO2H or OCF2CO2H R1 being different from hydrogen, -(CH2)m-NH2, -(CH2)m-NH(C1-C6)alc or -(CH2)m-N(C1- C6)alc2 when R4 is hydrogen, -(C1-C6)alc, -(C=O)n-(CH2)(0-5-NH2, -(C=O)n-(CH2)(0-5)- NH(C1-C6)alc or -(C=0)n-(CH2)(o-5-N(C1-C6)alc2 and R5 is a OSO3H group, or when R4 has all the values of the above R" except for heterocycle and n, o, p and q cannot all be O except when R" is hydrogen or CONH2, CONH(C1- C6)alc, CON(C1-C6)alc2 or heterocycle the invention relates to these compounds in the free form thereof or in zwitterion form or in the form of salts with pharmaceutically acceptable mineral or organic bases and acids, to the preparation thereof, and to the use thereof as antibacterial drugs.Linvention concerne des composés hétérocycliques azotés de formule (I) dans laquelle : R1 représente hydrogène, -(CH2)m-NH2, -(CH2)m-NH(C1-C6)alc, -(CH2)m-N(C1-C6)alc2, - (CH2)m-NH-C(NH)NH2 ou -(CH2)m-NH-CH=NH, m est égal à 1 ou 2 R2 et R3 forment ensemble un hétérocycle azoté à caractère aromatique à 5 sommets renfermant 1, 2 ou 3 atomes dazote, substitué sur un atome dazote par R4 R4 représente hydrogène, (C1-C6)alc ou
