Multi-center Study to Assess Safety, Tolerability and Efficacy of Topical Pravibismane in Moderate DFI Patients

Inclusion Criteria: * Has diabetes mellitus, according to the American Diabetes Association (ADA) criteria. * Has a skin ulcer located on or distal to the malleolus that is ≥ 4 weeks that is clinically documented, and presents with clinical manifestations of a moderate infection (i.e. erythema extending ≥ 2.0 cm from the wound margin), and not requiring hospitalization. * Has received no more than 36 hours of antibiotic therapy for the moderately infected ulcer prior to enrollment or there is clinical and/or microbiological evidence of failure of antibiotic treatment for the treatment of the moderately infected ulcer. * Has documented adequate arterial perfusion in the affected limb by biphasic or triphasic Doppler wave forms, a toe brachial index (TBI) ≥0.75, or an ankle brachial index (ABI) of \>0.9). * Has read and signed the Informed Consent Form (ICF) after the nature of the study has been fully explained. Exclusion Criteria: * Has proven or highly suspected, involvement of bone (i.e., osteomyelitis). * Has an ulcer due to Charcot arthropathy. * Has more than one concurrent, infected, diabetic foot wound on the study limb. * Is unwilling or unable to attend clinic visits and keep research appointments. * Is unwilling or unable to adhere to the systemic antibiotic treatment prescribed. * Is unwilling or unable to adhere to proper pressure off-loading of the foot wound (when needed) from enrollment through EOS as directed by the treating physician. * Has an untreated, uncontrolled, or poorly managed immunosuppressive and or autoimmune disorder. * Plans to use any topical antibiotics, herbals remedies (e.g., honey), alternative medicines or antimicrobials, either directly or by dressings on their infected DFU at any time from enrollment through the EOS visit. * Plans to receive treatment with larvae (maggots) for their infected DFU at any time from enrollment through the EOS visit. * Plans to receive treatment with advanced cellular therapies (e.g., Platelet-derived growth factor (PDGF), Cellular Tissue Products (CTP), granulocyte colony-stimulating factor (G CSF)) for their infected DFU at any time from enrollment through the EOS visit. * History of major medical noncompliance. * Any condition that has required treatment with any other bismuth containing compound within 2 weeks prior to enrollment through EOS visit (i.e., Kaopectate or Pepto-Bismol, including topical applications such as Xeroform). * Plans to receive treatment with Hyperbaric oxygen therapy (HBOT) or topical negative pressure wound therapy (NPWT) for their infected DFU at any time from enrollment through the EOS visit. * Glycated hemoglobin \>12%. * Has a serum creatinine, ALT, AST or Alkaline Phosphatase \>3 times the upper limit of the normal range of the local testing laboratory. * End stage renal disease requiring dialysis. * Has an absolute neutrophil count \<1000. * Has participated in an investigational trial to evaluate pharmaceuticals or biologics either concurrently or within the past 30 days. * Will undergo a planned surgical therapy beyond standard bedside debridement or incision and drainage, to treat the DFI after enrollment. * Has a known allergy to bismuth and/or MBN-101 excipients (methylcellulose, Tween 80 (polysorbate 80)). * Is immunocompromised and not well-managed due to illness \[human immunodeficiency virus (HIV), autoimmune disease\] or organ transplant. * Has a history of any type of cancer (excluding non-melanoma localized skin cancer or completely excised and cured carcinoma-in-situ of uterine cervix) unless the subject has been free of cancer for \> 5 years. * Developmental disability/significant psychological disorder that in the opinion of the investigator could impair the subject's ability to provide informed consent, participate in the study protocol or record study measures. * Active alcohol abuse (\> 14 drinks per week over the last 3 months) or substance abuse (current use of cocaine, heroin, or methamphetamines) or if drug or alcohol use will interfere with visits in clinic in the opinion of the investigator. * Has other medical condition(s) which, in the opinion of the Principal Investigator, would jeopardize the safety of the study subject or impact the validity of the study results.