This invention provides a compound of formula (I): or pharmaceutically acceptable salts thereof, wherein X1 and X2 are C or N, respectively; R1 and R2 are independently phenyl optionally substituted with a hydroxy group with proviso that X1 and X2 are not simultaneously C or N, when X1 is N, R1 is absent, and when X2 is N, R2 is absent; R3 is methyl or hydroxymethyl; R4 is formyl, hydroxymethyl or hydroxy C3-6 alkenyl; R5 is hydroxy, C3-6 alkenyl or hydroxy C3-6 alkenyl; or R4 and R5, together with the carbon atoms in the furopyridine ring to which they are attached, may form the following ring (to be fused with the furopyridine ring): with the proviso that when R3 is methyl and R5 is 2-buten-2-yl, X2 is not N. These compounds and pharmaceutical compositions containing such compounds are useful for treating infectious diseases caused by bacteria.