In Arm 1, eligible subjects will be treated with a single application of Nu-3 or placebo in 4 to 1 ratio to judge the initial safety of Nu-3 over a brief one (1) hour interval and 24-hr interval post application. Bisphosphocin Nu-3 will be applied topically to the chronic infected ulcer, covered with a non-abrasive bandage following the initial observation period. The subject will be released with verbal instructions to leave the bandage on the wound and return for a follow up visit within 24h ± 2h. At the follow up visit, the bandage will be removed, the ulcer visually examined and the subject cleared for the MAD Arm 2 based on the recommendation of the PI and absence of any SAEs.