Background: Community-acquired monomicrobial Pseudomonas necrotizing fasciitis [NF] is a rare and unclassified type of NF. Late recognition and using non-antipseudomonal antibiotics may lead to poor outcomes. This report describes the clinical features and management of Pseudomonas aeruginosa NF in a cancer patient.

Case Report: A 68-year-old Thai man with poorly controlled diabetes and advanced lung cancer, who was taking docetaxel for I2 days, was admitted to Chulabhorn Cancer Center. His medical history
suggested a prior minor injury to his left thigh. He presented with fever and an erythematous lesion in his left thigh and developed changes in consciousness and respiratory failure. Clinical features showed septic shock with diabetic ketoacidosis [DKA], a hyperosmolar hyperglycemic state [HHS], multiple foci of ecthyma gangrenosum, and soft tissue infection. He was then empirically
treated with meropenem, had resuscitation of hemodynamics, and DKA/HHS corrected. Central necrosis later developed with blebs on his left thigh. NF was diagnosed and necrotic tissue resection was
immediately performed. P. aeruginosa was isolated from hemocultures and tissue culture. A 2-week course of antibiotics with adequate tissue debridement improved clinical and microbiological
outcomes.

Conclusion: A case of monomicrobial P. aeruginosa NF was diagnosed after minor trauma in a severely immunocompromised host. The patient's excellent outcome was achieved by a high index of suspicion by physicians in host factors, prompt diagnosis, early anti-pseudomonal antibiotic treatment, good hemodynamic resuscitation, immune reversal therapy, and immediate surgical debridement.

Keywords: Pseudomonas necrotizing fasciitis, Soft tissue infection, Hemodynamics, P. aeruginosa, Tmmunocompromised host