Pseudomonas aeruginosa: A Rare Cause of Necrotizing Fasciitis

Necrotizing fasciitis (NF) is a rare but life-threatening soft tissue infection characterized by rapid progression, systemic toxicity, and high mortality. While Group A Streptococcus is the most common pathogen, Pseudomonas aeruginosa is an uncommon cause, typically reported in immunocompromised patients. We present the case of a 77-year-old male with chronic lymphocytic leukemia (CLL), chronic kidney disease, and other comorbidities who initially presented to an outside facility with three days of fever and left lower extremity pain. He was admitted with presumed cellulitis, and blood cultures grew Pseudomonas aeruginosa. Despite appropriate antibiotic therapy with vancomycin and ceftriaxone, the patient developed worsening pain, septic shock, rhabdomyolysis, and renal failure, prompting transfer to our facility for higher-level care. Examination revealed tense swelling of the left lower extremity, multiple bullae, and severe pain. Given concern for Pseudomonas NF, he underwent emergent above-the-knee amputation, followed by multiple debridements. He was subsequently transferred for advanced plastic surgical closure in stable condition. Pseudomonas aeruginosa remains a rare but severe cause of NF, particularly in immunocompromised patients with hematologic malignancies. Immunosuppression likely contributed to the unusual pathogen and aggressive clinical course in this case. Delayed diagnosis appears to be associated with increased mortality, underscoring the importance of timely blood cultures, broad-spectrum empiric coverage, and urgent surgical intervention. This case highlights the critical need for early recognition of Pseudomonas-associated NF and consideration of strict guidelines for high-risk populations to improve outcomes.