Pan-Resistant Pseudomonas aeruginosa Septic Shock in a Critically Ill Patient: A Case Report

Pseudomonas aeruginosa is a frequent cause of healthcare-associated infections and is increasingly encountered in extensively drug-resistant (XDR) or pan-drug-resistant (PDR) forms. Such strains leave clinicians with virtually no therapeutic options and carry high mortality.

We describe a 66-year-old man with chronic hypoxic respiratory failure, chronic kidney disease, and recurrent infections who was admitted with septic shock. Initial broad-spectrum antibiotics were ineffective, and cultures yielded PDR Pseudomonas aeruginosa, resistant to cefiderocol and with borderline colistin susceptibility (MIC 2 µg/mL). Antimicrobial susceptibility testing was performed by broth microdilution on a Thermo Fisher Sensititre™ GNX3F panel, with colistin MIC confirmed by reference broth microdilution; results were interpreted per EUCAST v13.0 (2025) and CLSI M100 (2025). Despite high-dose intravenous colistin, cefiderocol, and adjunctive amikacin, the infection persisted, leading to progressive multi-organ dysfunction. Colistin dosing was adjusted for renal insufficiency and subsequently for continuous renal replacement therapy (CRRT). Meropenem (MIC 8 µg/mL; resistant) was trialed in combination with colistin for potential pharmacodynamic synergy. After 12 days of intensive care, and following discussion with family, care was redirected to comfort measures, and the patient died. The cause of death was refractory septic shock due to PDR Pseudomonas aeruginosa with multi-organ failure.

This case illustrates the therapeutic futility posed by pan-drug-resistant (PDR) Pseudomonas aeruginosa. Colistin's limited efficacy at borderline MICs, compounded by renal impairment, constrained dosing. Even newer agents such as cefiderocol proved ineffective. Experimental therapies, including bacteriophages, novel β-lactamase inhibitors, and antimicrobial peptides, remain unavailable in most clinical settings.

PDR Pseudomonas aeruginosa represents an urgent global threat. Until novel therapies become accessible, stringent stewardship, infection control, and preventive strategies remain the most effective defenses.