The image shows dermatomal distribution of vesicular lesions which are suggestive of shingles/ herpes zoster. Acyclovir, Famiciclovir, valaciclovir and ganciclovir are nucleoside analogues which must be phosphorylated to nucleotide analogues in order to function. However, if viral strains are lacking in viral phosphorylating enzymes, this step is not possible. This renders these viral strains resistant to these drugs. However, Foscarnet is a pyrophosphate analogue which directly inhibits viral DNA polymerase and therefore, does not require viral phosphorylating enzymes. Another impoant drug is cidofovir, which is a nucleotide analogue and therefore, it also does not require viral phosphorylating enzymes and hence, useful in such cases.