Abstract: A compound of formula (I) for use in the prevention or treatment of a bacterial infection wherein: PX is selected from the group consisting of (P1), (P2) and (P3).

Abstract: A compound of Formula (II): for use in the prevention or treatment of a bacterial infection.

Abstract: A compound of formula (I): for use in the prevention or treatment of a bacterial infection wherein: A is either S or Se; RA is selected from: wherein: each of Y1, Y2, Y3, Y4 and Y9 is independently selected from CH or N, wherein at least three of Y1, Y2, Y3, Y4 and Y9 is CH; V is selected from O, CH—OR01, N—CO2—RC2 or N—RN2; one of Y5, Y6, Y7 and Y8 is selected from CH and N, and the others are CH; X is selected from NH, S or O; RC1 is selected from O—RO2 or NHRN1; RO1 is selected from H and C1-3 unbranched alkyl; RO2 is C1-3 unbranched alkyl; RN1 is selected from H and C1-3 unbranched alkyl; RN2 is C1-3 unbranched alkyl; RC2 is either C1-3 unbranched alkyl or C3-4 branched alkyl; RC3 is selected from C1-3 unbranched alkyl and C2H4CO2H; RC4 is either H or Me; RC5 is either H or Me; RC6 represents one or two optional methyl substituents; and n is an integer from 2 to 8.