SEVERE AND RECURRENT PSEUDOMONAS AERUGINOSA INFECTIONS IN CRITICALLY ILL PATIENTS: A CASE SERIES OF PNEUMONIA, SEPSIS, SEPTIC PULMONARY EMBOLI, AND DIABETIC KETOACIDOSIS

Background: Pseudomonas aeruginosa is an important opportunistic pathogen associated with severe healthcare-associatedinfections, particularly among critically ill patients. It can cause pneumonia, bloodstream infection, sepsis, abscesses, and othermetastatic complications. Treatment can be challenging because of its intrinsic and acquired antimicrobial resistancemechanisms. The clinical course may be further complicated by diabetes mellitus, diabetic ketoacidosis (DKA), acuterespiratory distress syndrome (ARDS), prolonged mechanical ventilation, and recurrent infection. Case presentations: Wedescribe three critically ill male patients with severe P. aeruginosa-associated infections requiring intensive care management.Case 1 was a 36-year-old man with newly diagnosed diabetes mellitus and DKA who developed severe P. aeruginosapneumonia complicated by ARDS, septic shock, acute kidney injury, and prolonged mechanical ventilation. Blood andendotracheal aspirate cultures repeatedly yielded P. aeruginosa, reported as susceptible to meropenem and resistant to colistinand polymyxin-B. After initial recovery and discharge, he was readmitted with fever and a left foot abscess. CT pulmonaryangiography demonstrated multiple pulmonary nodules and cavitary lesions suggestive of septic pulmonary emboli. Bloodand pus cultures again yielded P. aeruginosa. Source control was achieved by incision and drainage, and antimicrobial therapywas escalated to ceftazidime-avibactam.Case 2 was a 27-year-old man who presented with high-grade fever, right knee pain, jaundice, severe hypoxemia, andrespiratory failure. He required intubation, mechanical ventilation, prone positioning, and intensive care treatment. Bloodculture initially demonstrated Gram-negative bacilli subsequently identified as P. aeruginosa. He improved followingtreatment but was readmitted with recurrent fever, severe tachycardia, dyspnea, and persistent right knee symptoms. Theavailable records suggest possible musculoskeletal involvement; however, definitive microbiological confirmation fromsynovial fluid or other joint specimens was not available in the source material. Case 3 was a 25-year-old man with diabetesmellitus who presented with severe hyperglycemia, positive urine ketones, high-grade fever, profound hypoxemia, and clinicalfeatures of severe infection. He required emergency intubation, mechanical ventilation, intravenous insulin, fluid resuscitation,and broad-spectrum antimicrobial therapy. Blood and endotracheal cultures subsequently demonstrated P. aeruginosa, reportedas susceptible to meropenem and resistant to colistin. Following culture-directed antimicrobial therapy and metaboliccorrection, he improved and was successfully extubated. Conclusion: These cases demonstrate the heterogeneous andpotentially severe manifestations of P. aeruginosa infection in critically ill patients. Recurrent bacteremia should promptcareful reassessment for persistent or metastatic sources of infection and consideration of definitive source control. Severeinfection may coexist with or precipitate DKA and ARDS, requiring coordinated antimicrobial, metabolic, respiratory, andcritical-care management. Repeated microbiological assessment and antimicrobial susceptibility testing are essential forguiding therapy.