Antibacterial compounds

A compound of formula (I):

• wherein
• R1, R2, R3 and R4 each independently are selected from the group consisting of:
• hydrogen, halo, —CN, Rt1, —O—Rt2, —C(O)N(Rt3)(Rt4), —SO2Rt5, —N(H)SO2Rt6, —N(Rt7)(Rt8), aryl and heterocyclic group wherein said aryl and said heterocyclic group optionally substituted by one or more substituents selected from halo and C1-6 alkyl;
• Rt1, Rt2, Rt3, Rt4, Rt5, Rt6, Rt7 and Rt8 independently are hydrogen or C1-6 alkyl wherein said C1-6 alkyl is optionally substituted by one or more halo atoms, or, Rt3 and Rt4 and/or Rt7 and Rt8 may be linked together with the nitrogen atom to which they are attached to form a 3- to 7-membered ring, optionally containing one to three additional heteroatoms and optionally contain one to three double bonds;
• Zx is O or S;
• X is S or O;
• ring A is either:
• Rx is hydrogen or C1-6 alkyl wherein said C1-6 alkyl is optionally substituted by one or more substituents selected from the group consisting of fluoro, —CN, —ORx1, and —C(O)Rx2;
• Rx1 and Rx2 independently are hydrogen or C1-6 alkyl;
• Ry3 independently is hydrogen, halo, C1-6 alkyl, —ORy4, —C(O)—Ry5 or —CH2—ORy6;
• Ry4, Ry5 and Ry6 independently are hydrogen or C1-6 alkyl;
• wherein Ry1 is fluoro, chloro, C1-6 alkyl, —OH, —C(O)Ry5 or —CH2—ORy6;
• and Ry2 is —OH, C1-6 alkyl, —C(O)Ry5 or —CH2—ORy6
• or a pharmaceutically acceptable salt thereof.