Green Foot Discoloration Secondary to Pseudomonas aeruginosa in an Elderly Male.

Green discoloration of the skin is an uncommon clinical finding that can cause significant alarm among patients and caregivers. We present the case of a 92-year-old man residing in a nursing facility with a past medical history significant for hypertension, type 2 diabetes mellitus, stage 3a chronic kidney disease, chronic venous insufficiency, prior left ankle surgery with retained internal fixation hardware, and a history of deep venous thromboses who presented to the ED with acute-onset green discoloration of his left foot. The discoloration was first noticed by the nursing staff at his facility. The patient denied pain, fever, or chills. Physical examination revealed green discoloration of the plantar surface of the left foot, bilateral lower extremity edema with stasis dermatitis, chronic skin hyperkeratosis, onychomycosis, and a superficial skin laceration on the dorsal aspect of the foot. Laboratory evaluation demonstrated elevated blood urea nitrogen and creatinine levels consistent with acute kidney injury and a normal lactate level. Radiography showed diffuse soft tissue edema without fracture. The Infectious Diseases service was consulted. Clinical assessment determined that the green discoloration was attributable to Pseudomonas aeruginosa colonization, with secondary superimposed cellulitis arising from excoriations caused by ill-fitting footwear. The patient was treated with IV cefepime followed by step-down therapy with oral cephalexin and doxycycline, along with acetic acid soaks and wound care. Blood cultures remained negative. The patient demonstrated clinical improvement and was discharged to his nursing facility with wound care follow-up. This case highlights the clinical challenge of distinguishing Pseudomonas colonization from invasive infection in elderly patients with chronic skin changes and underscores the importance of a multidisciplinary approach involving infectious diseases and wound care.