Multidrug-Resistant Serratia marcescens Cavitary Pneumonia in an HIV Patient: A Case Report.

Serratia marcescens is an opportunistic gram-negative bacillus with both intrinsic and acquired resistance mechanisms, making it a challenging pathogen in immunocompromised individuals. We report a fatal case of cavitary pneumonia caused by multidrug-resistant S. marcescens in a 42-year-old HIV-positive man with chronic comorbidities, who presented with acute hypoxic respiratory failure and septic shock. Imaging revealed a large cavitary lesion in the right upper lobe, and cultures from blood, urine, and respiratory secretions confirmed S. marcescens with broad-spectrum antibiotic resistance. Despite aggressive medical management, including broad-spectrum antimicrobials, vasopressor support, bronchoscopy, and renal replacement therapy, the patient's condition deteriorated, resulting in death. This case underscores the rare but severe pulmonary manifestation of S. marcescens in immunocompromised hosts, emphasizing the importance of early recognition, infection control, and targeted antimicrobial therapy in managing such high-risk infections.