The invention relates to antibacterial compounds of formula I wherein U represents CH or N; V represents CH or N, provided that at least one of U and V does not represent N; R represents H, halogen, methyl, methoxy, cyano or ethynyl; either W represents a phenyl group substituted in para position with (C1-C3)alkyl, (C1-C3)alkoxy or (C1-C3)thioalkoxy and optionally in meta position with halogen, or W is a group having one of the formulae W1 and W2 below wherein Q is O or S and X is CH or N; and salts of such compounds.